President Reagan swept into office in 1980 on a wave of growing conservatism in the United States. But there are some signs that the trend is cresting and that the Reagan Revolution -- which profoundly affected the national agenda and the political parties -- may be peaking. Political analysts note these developments: Although President Reagan continues to enjoy a high approval rating, polls show a gap between the popularity of Mr. Reagan and public support for his domestic and foreign policies. Increasingly, for instance, most Americans are opposed to further cuts in social programs and increases in defense spending.
The much-talked-about historic electoral ``realignment'' toward the Republican Party appears to be subsiding. One indication of this is that the GOP's campaign in four states to lure Democrats to switch party affiliation is not proving quite as successful as had been hoped.
This doesn't mean the Democrats are back in fashion and gaining as a result. The Democratic Party is still groping for new directions and image in the wake of the decline of New Deal and Great Society liberalism. If the Republicans are not yet the majority party, the Democrats glumly worry about how to regain their preeminent status.
But even conservative analysts suggest that the pendulum is swinging back to a dominant current in American politics -- the mainstream center. And some, like Reagan critic Kevin Phillips (who argues the GOP misread the 1980 and 1984 election results), forecast that the Reagan Revolution will stall in the next two years.
David Gergen, writing in the current issue of Public Opinion magazine, concludes that under Reagan the country remains solidly middle-of-the-road. He cites a CBS News/New York Times survey showing Americans leaving the conservative camp since Reagan came into office: 37 percent identified themselves as conservative in 1981 and only 30 percent in 1985. The largest number (about 40 percent) continue to think of themselves as ``moderates,'' while 16 percent in 1981 said they considered themselves liberal c ompared with 19 percent in 1985.
Analyzing opinion polls over five years, Mr. Gergen, a former Reagan White House aide, also concludes that:
Trust in government is growing again because Reagan has restored confidence in the capacity to govern.
Public approval of spending cuts is declining.
There is no longer a desire to increase military spending because the Reagan rearmament has increased a sense of security.
Americans now are more relaxed about the Soviet Union, and continue to favor an arms control accord and to oppose US involvement in areas like Nicaragua.
A final observation is that ``social conservatism isn't catching fire.'' Reagan has made progress in getting public support for the death penalty, Gergen says. But there is no strong political push for voluntary prayer in the schools, even though most Americans support it; the Equal Rights Amendment continues to have strong backing; and the public does not favor reversing the Supreme Court's decision on abortion.
``Adding up all the numbers, it's difficult to argue that Reagan is presiding over a conservative revolution,'' writes Gergen. ``The man himself has taken a firm hold upon the public imagination, and he has opened the door for his party, but the public isn't flooding through it.''
``If anything, the country today appears to be more mainstream than when Reagan took office, and there is a greater desire to keep government just about the way it is -- with an arms control agreement thrown in for good measure,'' Gergen says.
William Schneider, a political scientist at the American Enterprise Institute, agrees there is no popular consensus behind a further conservative revolution, as there was in 1981. Four years ago, he says, Americans felt a sense of crisis because of roaring inflation and allowed Reagan to stay the course even during a deep recession.
``Conservatism and Reaganism have not lost popularity, but they may be at their peak,'' he says. ``We're at the point now where a decision has to be made whether we're going to change the role of government in some fundamental way. So far the answer is no.''
The practical test of such analyses will, of course, come in the '86 and '88 elections. The Republican Party is vigorously trying to capitalize on Reagan's popularity to build up GOP ranks, create a majority at the grass-roots levels, solidify the realignment at the national level, and keep control of the White House.
But that may prove difficult. According to the Tampa Tribune and other local press accounts, a GOP campaign called ``Operation Open Door'' aimed at registering 100,000 Democrats in Florida, Louisiana, North Carolina, and Pennsylania has fallen short of its goals. The Republican National Committee will release official figures this week.
Mr. Phillips, editor of the conservative newsletter American Political Report (APR), believes Reagan has overreached ideologically with his deficit-producing budget policy and second-term ``get the government out of the economy'' agenda.
This, says APR, has put the Republicans and the administration ``on a crash course with public opinion'' on such issues as trade, agriculture, tax policy, social security, and domestic spending. It threatens to undercut GOP hopes in 1986, it adds, unless the administration tackles the deficit with a tax increase and backs off its attack on middle-class programs.
Looking at conservatism historically, Phillips suggests that the current conservative-right tide began not in 1980 with the election of Ronald Reagan but in 1968 when Richard Nixon was voted into office. The Watergate crisis and its political impact interrupted it. Hence ``the Reagan Era represents not a new trend but a later-stage over-ideologization of a more moderate conservative trend,'' APR says.
According to Phillips' analysis, watershed elections in American history have come at 28- to 36-year intervals (1800, 1828, 1860, 1896, and 1932), with a basic redirection of the nation taking place in the first two decades and then tapering off as a new cycle began. If 1968 marked a pivotal year for conservatism, the two decades would end in 1988, says Phillips.