SINCE RONALD REAGAN'S second landslide victory, many have asked if a major realignment is under way in American politics that might indure for decades. The questions usually are: Is Reagan's electoral coalition likely to survive? Will its members also support Republican candidates for congressional and state office?

However, the issue of realignment is broader than these questions suggest. The half-dozen party systems that have governed the United States since Jefferson have been distinguished by more than their electoral bases. At least five characteristics distinguish a durable and stable regime in American national politics:

*Its leaders successfully define the central issues of national politics -- that is, the content of the nation's political agenda.

*A stable regime must forge a coalition of interests stronger than that of its opponents.

*It develops an ideology that plausibly presents the interests of its supporters as general or common interests.

*A durable regime constructs governmental institutions that enable it to enact policies beneficial to its supporters.

*To remain in power a regime must foster prosperity, and finance the flow of public benefits to its supporters without slowing the growth of the national economy.

The regime constructed by Ronald Reagan seems to meet all of these criteria and thus could last long after Reagan himself leaves office.

The Reagan administration has been quite successful in defining the central issues of national politics by shifting national attention from the expenditure to the revenue side of the federal budget.

From the 1930s through the 1960s, the Democrats entrenched themselves by channeling public funds to the party's constituent groups -- crop subsidies for farmers, Social Security for the elderly, Great Society programs for blacks, and so forth. Throughout these decades, Democratic candidates campaigned for public office by warning each bloc of voters that the Republicans planned to withhold or dilute their benefits.

In a parallel fashion, Ronald Reagan compaigned against Walter Mondale in 1984 by warning voters that the Democrats wanted to take their tax cut away. Republicans will be able to continue to do that in the future because the indexation provisions of the 1981 tax act in effect turn the Reagan tax cut into an entitlement program for the middle and upper classes. Every year these voters will be entitled to a further cut in nominal tax rates, and every other year Republican candidates can warn voters that the Democrats have a plan to omit it.

The Reagan tax cuts also create a structural imbalance between public revenues and expenditures that makes it difficult for the Democrats to appeal to voters by promising to enact new expenditure programs. Rather, the Democrats have been compelled since 1981 to fight on terrain defined by Ronald Reagan -- to propose budget cuts of their own. This is terrain on which it is difficult for the Democrats to win.

This situation points to the second characteristic of a dominant regime -- its forging of a coalition that can win elections, while weakening the opposition's coalition.

In 1984 Ronald Reagan won considerable support not only among traditional Republican voters, but also among Southerners, Catholics and blue collar workers who had begun to vote against Democratic presidential candidates because of the party's association with civil-rights and antiwar protesters. In addition, Reagan won solid support among young, college-educated professionals -- "yuppies" -- the very social group that had been sympathetic to these protests in earlier years.

Reaganites regard these yuppies as a crucial swing group. That is why Reagan has done almost nothing on behalf of the New Right "family" issues that are anathema to cosmopolitan professionals. Similarly, to meet the threat of the nuclear freeze movement -- Reagan's opponents attempt to mobilize the old antiwar constituency against him -- the president was determined to enter into arms-control negotiations prior to the 1984 election.

The social group that includes the "yuppies" was labeled the "New Class" by sociologists in the 1960s. It is that segment of the nation's upper class whose chief asset is human capital -- high levels of education -- rather than financial capital. It has been argued that the New Class is inherently liberal, because its members have greater leverage in the public than in the private sector. In point of fact, however, this class has no inherent ideological tendencies.

Ronald Reagan has undertaken to divide its members with his tax reductions and domestic budget cuts -- expanding opportunities for middle-class professionals in the private sector, while restricting opportunities in the public and non-profit sectors. Those college-educated professionals who are in a position to take advantage of these opportunities are being attracted into the Republican Party. Those who are not -- teachers, social workers, and college professors, for example -- remain attached to the Democratic Party.

One striking suggestion that Reagan's strategy may succeed: The New York Times/CBS 1984 exit poll reported that of those who use a computer on their job or at home, 62 percent voted for Ronald Reagan in 1984.

Reagan's tax and budget cuts may establish durable linkages between the GOP and upper-middle-class professionals in the private sector, but they also are likely to drive ever more firmly into the Democratic camp members of the middle class who work in the public and non-profit sectors, such as teachers and librarians. These voters will increasingly advocate ideas such as "comparable worth" -- which asserts that wages should not be determined by the market, but by the individual's level of education -- to defend themselves against cuts in domestic spending.

In addition, the Reagan administration has greatly weakened organized labor. By driving up real interest rates and the value of the dollar, it has eroded the competitiveness of many American industries, increasing unemployment and reducing labor's bargaining power. It is a mark of the desperation of labor in the face of Reaganite policies that union leaders are prepared to join forces with old antagonists -- feminists, environmentalists and peace groups. The restrictions on corporate managers advocated by these groups, in turn, has driven business ever more firmly into the arms of the GOP.

This leads to the third requisite of a stable regime -- that it develop a legitimating ideology that plausibly presents the interests of its key supporters as the common good.

In recent years businessmen have contributed a good deal of money to institutions such as the American Enterprise Institute, the Heritage Foundation, and the Hoover Institution, and these have financed a flowering of conservative thought.

A mark of the success of this ideological offensive is the voters' increasing skepticism toward the public philosophy of the New Deal -- interest-group liberalism. Note the widespread criticism of Walter Mondale for caving in to the Democratic Party's "special- interest groups." This indicates the failure of the Democrats to plausibly present the interests of their core supporters -- such as feminists, blacks, and gays -- as a plausible vision of the common good.

By contrast, the Republicans under Ronald Reagan have been remarkably successful in presenting the interests of their core supporters as common interests. The 1981 tax cut was enacted on the premise that everyone would benefit if taxes on the wealthy and on business were cut. Similarly, the claims of equity embodied in the administration's tax simplification plan are sufficiently persuasive that even Common Cause, the liberal public- interest lobby, announced its support for the plan.

It is Ronald Reagan's political genius to have persuaded millions of Americans that there is a relationship between the performance of American athletes at the Olympics, on the one hand, and the administration's arms build-up, on the other -- both are examples of America's new spirit, of America's coming back.

Clearly, the Republicans have elaborated a vision of a nation that is prosperous at home and respected abroad -- a vision that millions of working-, middle-, and upper-class Americans alike find compelling. It is not inconceivable that they will continue to find it compelling in years to come.

A fourth characteristic of a stable regime is its ability to alter political processes that had worked to the advantage of its predecessors, and to establish nw institutions that enable it to implement policies benefiting its supporters.

Since 1980, the Reagan regime and its supporters have systematically attacked the organizational power bases of their opponents. Reagan appointees have undertaken to "defund the left" -- for example, halting the flow of federal funds to legal-services agencies that file class-action suits on behalf of the poor. In addition, the Internal Revenue Service has threatened to withdraw the tax exemptions of nonprofit organizations that engage in political activism.

The administration's tax-reform proposal, by eliminating the deduction for state and local taxes, assaults another institutional bastion of President Reagan's opponents -- state and local bureaucracies in the Northeast. If this proposal is enacted it will place the predominantly Democratic state and local governments in the high-tax Northeast in a bind.

They will either have to cut taxes and fire thousands of public employees (whose unions play an important role in the Democratic party), or they will encourage business firms and taxpayers to flee to regions of the country where taxes are lower, thereby suffering a decline in wealth and population -- and a loss of votes in the Electoral College.

The administration would also undermine Democratic Party strength by eliminating public financing of presidential campaigns based upon a $1 checkoff on federal tax returns. The Republican party can raise far more money from private sources than can the Democrats.

Reagan supporters have also sought to weaken or gain control of other institutions through which their opponents had exercised influence in the 1970s. This is the political significance, for example, of the recent spate of libel suits against the news media -- most prominently the Westmoreland and Sharon suits against CBS and Time magazine.

These suits are encouraged and often financed by conservative organizations, such as the Capital Legal Foundation. When journalists and liberals charge that the threat of such suits could discourage the press from raising questions about the conduct of public officials, these conservative organizations are quite forthright in saying that this is precisely their intention.

To counter the phenomenon of liberal political forces exercising influence throught the federal judiciary, conservative public-interest law firms are now contesting suits filed by environmental and consumer groups. And, as Geraldine Ferraro discovered, they are beginning to make use of the ethics-in- government statutes that Common Cause drafted in the 1970s to create new categories of crimes that could be committed by public officials it opposed, and could be used to drive these public officials from office.

On the affirmative side, the Reagan administration has appointed a number of eminent conservative legal scholars to federal appeals courts -- most notably, Robert Bork and Ralph K. Winter of Yale, and Antonin Scalia and Richard Posner of the University of Chicago. By appointing these men, Reaganites clearly seek not simply to ensure that conservative judges will outnumber liberals on the federal bench, they also seek to stage an intellectual counterrevolution.

Finally, conservatives gained a majority in what had been the liberal bastion of the Senate, in part through negative ad campaigns financed by conservative PACs. The fear of providing ammunition for such campaigns now makes liberal senators think twice before deciding how to vote on every roll call. This may help to explain why the Senate Democrats have offered little in the way of effective resistance to President Reagan's initiatives.

With one major exception, the Reaganites have done more to attack the power bases of their opponents than they have to construct new institutions. That exception, however, is important. The GOP has built a national party apparatus that raises enormous sums of money for congressional elections, and plays a leading role in recruiting attractive Republican candidates to run in them.

Finally, if a regime is to endure and dominate national politics over several decades, it must finance its expenditures in ways that do not gravely injure the economy. If the Reagan regime has its Achilles heel, it is the enormous budget and trade deficits that have kept real interest rates and the value of the dollar at high levels, restricting business investment and the competitiveness of American firms.

However, the budget deficit should not be seen simply as a threat. By making it difficult for politicians to appeal for votes by proposing new public expenditures, the budget deficit hamstrings Democrats.

In addition, the trade deficit functions as a novel revenue-collection apparatus that enables the Reaganites to fund their budget deficits without raising taxes and alienating their political constituency. By increasing the value of the dollar, the Reagan administration encourages Americans to purchase foreign -- most notably, Japanese -- goods. At the same time, America's high interest rates and political stability encourage foreign bankers -- again most notably, the Japanese -- to purchase U.S. Treasury securities with the profits their nation's manufacturers make selling goods in the United States.

Thus, during the 1980s what might be called "Toyota dollars" are being recycled by Japanese banks, much as "petrodollars" were recycled by American banks in the 1970s. These Toyota dollars are being used to help finance the Reagan deficits.

While Americans, in their capacity as voters, demonstrated in 1984 that they oppose increased taxation as a means of financing the federal government's expenditures, as consumers they willingly -- indeed, enthusiastically -- hand over billions of dollars that will be used for this purpose whenever they purchase Japanese and other foreign- made goods.

To be sure, the government's fiscal practices cannot be continued indefinitely without totally decimating American industry and consuming much of the world's capital. The expenditures that help produce these deficits, however, may contribute to the solution of the very economic problems that deficits create.

The Reagan administration's enormous military build-up can be seen as a central component of Reaganite "industrial policy." For example, research for the "Star Wars" program, as Robert Reich notes, "could create whole new generations of telecommunications and computer-related products that could underpin information-processing systems in the next century."

Combined with efforts to reduce the labor costs of American industry by weakening unions and curtailing social spending, and to reduce other production costs by loosening federal regulations, this industrial reconstruction may help restore the international competitiveness of leading sectors of the American economy. If this effort succeeds, the Reaganites will not only have devised a long-term solution to the deficit problem, but also could fulfill the final precondition for an enduring reconstitution of American politics.

Some pundits argue that 1980 and 1984 were not critical elections, and that Ronald Reagan will not leave an enduring imprint on American politics. This skepticism may, of course, ultimately prove to have been warranted. But it does fail to pay heed to a central characteristic of Reaganism. Ronald Reagan is not Franklin Roosevelt or Lyndon Johnson. He does not want Congress to enact scores of new domestic programs.

To the contrary, Reagan wants to reduce the scope of the federal government's involvement in domestic affairs, and the indexation provisions of the 1981 tax cut may well make it unnecessary for Reagan and his successors to wage major budget battles in Congress each year to accomplish this goal. During the first five years of Ronald Reagan's presidency, for example, Congress has not enacted a single new major domestic spending program.

In this way, the structural imbalance between federal revenues and expenditures could prove to be the functional equivalent of an organic statute for a new Reagan regime. This would work to the advantage of the Reagan coalition even if the Democrats were to control both houses of Congress. Thus, whether or not there has yet been an enduring change in the conduct of American electoral politics, we have already witnessed a critical transformation in the politics of policymaking in the United States.

The success of Ronald Reagan's efforts to reorient politics and government in the United States is not guaranteed. It is yet to be demonstrated that tax policy can be made as compelling to voters on a continuing basis as New Deal expenditure programs proved to be. Moreover, the Reagan economic strategy is a high-risk venture and the enormous budget deficits the administration has tolerated may indeed lead to the disasters so many economists have predicted.

Uncertain as they may be, however, prospects for enduring realignment in American politics are stronger today than they have been for at least a generation.