The party system may be studied in many ways. Party membership, apart from the professional party worker, ranges from the voluntary (that is, the "independents") to the traditional (that is, the "rock-ribbed" and "die-hard"). Party principles may be clear or they may be difficult of definition. Party has been a feature of American political life from almost the beginning of the federal government and has often been identified with American individualism. It has also been connected with the traditional system of geographic representation under the majority principle. There are so many ways of looking at such a diffused system of party government as America has had that it seems justifiable to take up party also as a form of pluralism and to examine American parties in that light.
The weakness of party principle, it may then be suggested, is associated with the general weakness of political pluralism in American thought. And the dependence of party upon the majority principle in its traditional form is further associated with the weakness of pluralistic thinking. No slight to the complexity of party composition and party history is meant when such bald statements of relationships are made. Rather, the hope is to make clear that the traditional direct representation with the majority principle as an idea of representation is peculiar to the American party system as it has developed, and that pluralistic representation is not easily compatible with the historical idea of party.
The party system has its own pluralism, which it offers in opposition to the demands of more rigid pluralists. In America, most of the time, it is a dualism which offers to the country two combinations of proposals in return for a lease on the state. Each combination has, in addition to its professionals and traditional followers, voluntary supporters who are excited by convictions of righteousness and wish to make over the government in their own image by carrying the necessary majority or plurality. Simultaneously in operation, therefore, are the forces of unitary representation and pluralist representation. Subjectively, the traditional direct representation is being carried out and, objectively, pluralism faces the majority implacably. Professor Merriam has described the process to good effect in his Systematic Politics:
"This formal-informal status of the party, this responsible-irresponsible position in the political society, this uncompromising-compromising attitude, may seem to some to be inconsistent with the genius of organized government. If we think, however, of the necessity of combining right and might in authority, if we think of the desirability of organizing the consent of the governed and yet maintaining a government which cannot stop to ask consent for every act, the role of the party becomes clearer. Without the party, centralized authority may be able to bear down opposition too easily. The pressure for more and more is likely to be met by less and less effective opposition. With the party, however, the criticism and opposition of the "outs" may grow more and more as important groups and personalities are kept longer and longer out of political responsibility. The overthrow of the ruling party becomes more and more likely under such conditions, unless indeed material concessions are made by those in authority. In any case, the spirit of criticism of government, as well as that responsible defense, is kept alive, even at the price of unfair criticism and unfair defense. The important goal is not, however, keeping the party as such alive as it is keeping the consent of the governed alive -- reconciling the formal with the informal government. 
The party, therefore, is never completely politicized, never sovereign, never secure, and is always seeking the greatest number to represent, always seeking to represent unanimity.
A good deal of discussion has gone to explain the persistence of the two-party system in America. Sometimes, in desperation at the insufficiency of correlative data, the phenomenon has been ascribed to the "temperament" of the American people. This approach might not be altogether barren of results, provided that "temperament" be used as an opening and not as an excuse to drop the matter. Our traditional direct representation tends to admit of only a unified collective effort of the community. The idea of "presentation" and "delegation" toward which it veers is a unilateral idea. "Dissent" is always in process of being overcome by "unanimity". The final consensus and "presentation" is always just around the corner. Specialization of political function is not acceptable to this way of thinking. But party bureaucracy unfounded on principle is, if not desirable, at least not contradictory.
It is possible to surmise, then, that a most powerful way of thinking about representation has been all along associated with a simple party structure. "Mass presentation" has shunned the admission of diversity of principle. Both de Tocqueville and Ostrogorski mentioned the uneasiness and shame of insurgency.
But if one party can thus be accounted for, what convincing explanation can be offered for the second party? The second party resolves itself into a state of "becoming." Since "fixed interests" are uncongenial to the idea of mass representation, so is the static party of fixed principle. American party history is the story of one party, with a second "becoming." The rational "meaninglessness" of parties thus becomes meaningful: psychologically, plurality is unity.
On its official side, the party is unitary; on its unofficial side, it is pluralistic. It is consensus while it tries to create consensus. Its success in America has depended on its maintaining the double role. If it tends just a little to far in the direction of principle, it loses its attraction as a unitary party, its pluralism becomes evident, and its followers desert in large numbers. There are many evidences of its success in straddling the fence. For example, its lack of an intelligible program and leadership is often criticized. The composition of the party membership, though, is the best evidence of the success of the American party. Scarcely any part of the active membership is voluntary. Shifting from one party to another is much more acceptable to the mind of the people than participating in a third party movement.
So the extent of party pluralism in America is not great, though the composition of party following exhibits considerable pluralistic representation. Each party in fact organizes within itself the same pluralistic components -- business, labor, Negroes, women, religions, nationalities, and sectionalisms. Each group is found in each party, and therefore the parallelisms of composition tend to make a complete, incipient state out of each party; hence, the parties tend to mutuality of interests. Since each party must treat its samples of the political cosmos fairly in order that they may be adequate samples, the voice of each as an interest tends to become weaker while its voice as a group of interested individuals tends to grow stronger. American party pluralism, in other words, tends to sap the vitality of essential pluralism and that is why proper pluralists have never been happy with party pluralism.
Weak as it is, the vertical pluralism of the party is rendered more feeble by the federalism of which it must take account. Federalism, while in theory a system of dual sovereignties, is from another viewpoint a species of geographical pluralism. As sovereignty, federalism can claim absolute rights, but in America, over the past century, federalism has lost many of its sovereign implications and has come to mean more properly a form of pluralism through vertical decentralization of governmental authority. The party must organize both the clusters of local values which are constitutionally and traditionally entrenched, forming a pluralism, and the vertical pluralism of the party. The weakness of party pluralism, therefore, evidences the strength of federalistic pluralism from the standpoint of local interests. The vagueness of the general party symbolism strengthens the representative nature of the party in reference to the local pluralisms. It is representation of an expressive and bureaucratic kind which, like that of the king of England, grants satisfaction without imposing active authority.
Federalism, however, with one form of pluralism, poses problems to another form of pluralism which is based on the more modern needs of a centralized economy of interconnecting elements. The latter pluralism is that of business, labor, racial and religious groups, separated for the moment from the "national" interest which demands representation of the whole nation for certain things. The answer to this conflict of pluralisms in the past has come primarily from the courts and from the lobbies. Each, unconventionally assigned large de facto powers, has kindled the fires of the new pluralism at the expense of the old. Both, indeed, have furnished a third house of representation to the House of Representative, which represents in major part the nation, and the Senate, which in origin represents the states. The role of the courts is placed with the section on business representation, but the question of the lobbies may be discussed here, inasmuch as it is intimately connected with the nature of the party system.
The attitude of the public and of the courts was generally hostile to the lobby throughout the nineteenth century. A large part of the public never changed its attitude. But the lobby changed. It became crystallized as a mode of political pressure and took on the outward semblance of an institution. It espoused principles, corresponded with the press, the public, and the legislators, and finally declared itself confirmed in devotion to the public welfare. At this point, around the turn of the twentieth century, the advisability of entering into the lobbying field suggested itself to economic groups which had hitherto considered lobbying the pernicious and natural course of their enemies. The popular impression had been that representation of the people had been undermined and dissolved by the activities of lobbies representing special interests at the capitals of state and nation. The public in general never did quite realize that what it sought under traditional representative system had never been there at all, that the representation of the whole people was never an organized policy in American politics. "Popular" lobbies, therefore, entered the field of group pressure later than did the corporative interests, which had their origin in the speculators about whom a journalist of the First Congress wrote: "I do not know that pecuniary influence has actually been used, but I am certain that every other kind of management has been practiced...."
Joining the lobbying process was considered by the "popular" groups as a measure of self-defense. In the next generation, lobbying came to be considered an inevitable part of the legislative process. It is true that Hamilton, writing in the Federalist, did not consider that the problem of representing all interests in the society was serious. He thought that the general divisions of landed, commercial, and professional interests would find their way into the Congress and might represent the interests of the other classes sufficiently well. Without an express provision in the Constitution for occupational representation, he felt that the idea of detailed representation was quite impossible of fulfillment. Yet this would not mean the loss of freedom of the vote. For, under natural conditions, the merchants would represent the artisans and tradesmen, the large landowners would represent the small farmers, and the learned professions would conciliate and represent all by their essential neutrality.
Hamilton might have thought the matter more serious if he had foreseen the extent of the Industrial Revolution, the degree to which state and even national government would be subjected to the majority principle, and the coming of universal suffrage. For under such conditions, the party which developed could not perform its basic task of unifying a majority without conceding the important task of representing interests. Professor Herring, in his trailblazing study of Group Representation Before Congress, described the change:
"Political conditions are in a constant state of flux, and as one form of representation declines, another arises.... The party has definitely established itself as a unifying agency in government, but is rapidly losing its position as a formulator of policies and a leader of political thought."
And again," the minority groups arose to obtain from the government legislative action that they could not get through the political parties."
What are the salient characteristics of this recently developed mode of representation? Primary to our interest in American ideas of politics is the fact that lobbying as a mode of representation is obscurely known and little appreciated. The refusal to acknowledge its place in government has hindered the fixing of its organization and responsibility. The Constitution itself under the First Amendment has protected the lobby from the full force of public sentiment, since that Amendment guarantees the right "to petition the government for a redress of grievances." But that is a negative condition rather than a positive organization of the activity. Thirty-six states and the federal government have passed laws regulating the conduct of lobbies. Although the attitude of regulations has changed since the first days of lobbying legislation, when California called lobbying a felony and Georgia called it a crime, the recent legislation stops far short of a positive construction of lobbying activities into a mode of representation. The prohibition of flagrant abuses, the requirement of registration and financial reporting have been the substance of most legislation.
The participation of the lobbies in proposing legislation has only recently been studied,  and popular opinion, despite the efforts of writers like Bryce and Wilson, has never been able to focus on the lobby's most common mode of ingress into the legislative process, the private bill and the committee. Like drunkenness during prohibition, the prevalence of the lobby was denied and its abuses concealed. In the optimistic flush of the "Gay Twenties," a proposal was made to erect a central office building for lobbies in Washington, but the convenient project was abandoned when it was realized that the lobbyists would not move into the building and the legislators would not visit it.
Another important point about lobbying representation is that the constituency of lobbyists is well-defined and is dictatorial in respect to him. Professor Herring, who describes lobbying as "part of the American system of representation"  in one place, and calls it "Supplemental Representation" in another,  says that "these men regard themselves as the representatives of the voters who compose the membership of their respective leagues and association.... Most lobbyists claim that they are simply carrying out such instructions" as their organizations give them. They connect and communicate with their constituents back home, thence with the constituencies of the legislators with whom they deal. The lobbyist with an imperative mandate from a small constituency is thus counterpoised against the legislator with a vague mandate from a large constituency. Whose mandate shall prevail depends on many personal and social factors.
Formal occupational representation has been even less popular in America than informal lobbying. Although Americans like William MacDonald,  M.B. Reckitt,  Mary P. Follett,  Arthur N. Holcombe,  and Ernest S. Griffith made serious recommendations for occupational representation, and some textbook writers on government gave passing endorsement to the idea, the typical attitude was that expressed by Robert Luce, who wrote that "were group interest to be enthroned, legislative bodies, already harassed by the lobbies of groups, would find themselves exposed to double the pressure."
Americans concerned with the reform of representation tended to prefer proportional representation, believing, like Paul Douglas, that the problems of occupational classification for representative purposes would be most difficult. They felt that the high mobility of labor would make it hard to fix occupational groups in the system, that occupational representation would in no way provide for the representation of minorities within the occupations, that it would not provide protection from machine-dominated politics, and that it would prevent men from voting outside their industry and contributing intelligent direction along more general lines.