Washington — Pluralism persists in the American body politic. Exulting in his 49-state election victory, Ronald Reagan is poised to continue the basic conservative approach to government he launched four years ago.
But he does not have a mandate for a move further to the right in his second term. The American people, while electing a Republican President for the fourth time in the last five elections, stopped short of giving Mr. Reagan the strength he needs in the US Congress to enact his conservative agenda. The Republicans only partly recovered the losses they sustained in the House of Representatives in 1982. And their majority in the Senate was reduced by two seats.
This bifurcated public mood will act as a brake on any rightward ideological swing, political experts say. Divided government will continue to pose a challenge to resolving controversies in such urgent areas as nuclear arms control, budget deficits, and immigration reform.
Moreover, Reagan will be a lame-duck president in his second term as the next election cycle looms and the political battle for leadership succession begins in both the Democratic and Republican Parties.
''This is no mandate to the far right,'' says presidential scholar Robert Murray of Pennsylvania State University. ''The country as a whole is fairly satisfied with a Republican President who has stuck to a moderate or slight right course. But they persisted in electing Democrats at regional and local levels. With this kind of surge for Reagan you would have expected more of a coattail effect.''
Whatever the difficulties ahead, for the moment President Reagan can bask in the most impressive landslide at the presidential level since 1936. He captured every state but Minnesota and the District of Columbia. He swept up the entire American middle class, carrying the young people, the majority of women, the elderly, most ethnic groups, the once-Democratic vote among Catholics, blue-collar workers, farmers, and even millions of voters of low income. Democratic challenger Walter Mondale made inroads only among black, Jewish, unemployed, and low-income voters.
According to the final count, Reagan won 525 electoral votes and Mondale, 13. Reagan also garnered 59 percent of the popular vote, as against 41 percent for Mondale. In 1980 Reagan won only 50.7 percent of the vote.
Political analysts attribute the Reagan triumph to economic prosperity, peace , and the image of strong presidential leadership. Bucking a more buoyant, patriotic, and self-confident national mood simply proved an impossible task for the man from Minnesota. Mr. Mondale himself suggests Americans were inclined to give Reagan the benefit of the doubt after so many one-term presidencies.
''No one could have stopped Reagan,'' says presidential scholar Stephen Wayne , of George Washington University. ''The American people have ratified their presidency and they have done it in striking numbers. They have given him a resounding vote of confidence.''
''It's another personal triumph for a popular president, as in 1956 and 1972, '' says James Sundquist, a political scientist at the Brookings Institution. ''But it's not a great Republican victory - they have fewer senators, congressmen, and governors than four years ago. So it's not an earthquake or a realignment.''
Thomas E. Cronin, author of ''The State of the Presidency,'' suggests that the Reagan triumph was basically one of personality over issues, inasmuch as Americans do not go along with the President on many questions. But he says that the present conservative climate in the country is not to be underestimated.
''On the question of the role of government, the American people are in concert with him,'' Dr. Cronin remarks. ''They do like the idea of a rollback to the days when government was less intrusive. Reagan has been a conservative, and that fits well with the American mood.''
Looking ahead to his second term, the question now being asked is what specifically President Reagan has on his agenda and how he expects to accomplish it. During the campaign the President never spelled out plans for the future, running primarily on his record. But he and his aides have indicated a desire to achieve the following:
* A nuclear-arms-reduction agreement with the Soviet Union.
* A tax-simplification reform that would broaden the tax base and provide more revenue for closing the budget deficits.
* Further spending cuts to scale back government, tackling such areas as medicare and retirement benefits.
* A balanced-budget amendment.
* Completion of the military buildup.
* Further easing of environmental laws.
* ''Enterprise zones'' in poor urban areas to create jobs.
* Line-item veto power for the president.
* Such social goals as a school-prayer amendment, tuition-tax credits, and an anti-abortion amendment.
The President's principal domestic priority is to keep the economy on a forward track. Most economists believe that, unless Reagan vigorously tackles the deficits, the economy faces serious problems. But he must do this soon in the new term, and before there is another cyclical recession, when reducing the deficit would be even more difficult.
Some analysts suggest that the President has an opportunity to forge an economic program that would have bipartisan support. ''If that ended up with a meaningful effect on the budget deficit, that could put the Republicans in a position to hang in for a long time to come,'' says congressional expert Thomas Mann. ''The election results take some of the wind out of the sails of the most aggressive supply-side House Republicans and give the President a chance to build a coalition that stretches across the parties.''
If, on the other hand, Reagan sticks with his theory that the economy will ''outgrow'' the deficits, as the supply-siders believe, he could decide to do nothing.
Allen Schick, a budget specialist at the University of Maryland, predicts ''trench warfare'' in all but the early months of the second Reagan administration, with Congress and the President battling over taxes, spending cuts, and defense increases. But he also suggests Reagan could adopt one of two strategies on the budget: one, a blitzkrieg operation which he employed with success in 1981 during the ''window of opportunity'' in the first six months; or , two, a bipartisan effort where even the President might modify the budget process in the executive branch and call in congressional leaders before he submits his budget.
''It will be rough on the domestic front,'' says Dr. Schick, ''just as it was in the Eisenhower second term. Reagan, if he goes ahead with his domestic agenda , faces 31/2 years of fighting and then a severe Senate problem in 1986. And Tip O'Neill has indicated that any tax increase will have to have the President's signature on it if the Democrats are to go along.''
Dr. Sundquist also sees the Democrats sitting still in Congress and letting the President take the onus for the budget deficits. ''There will be even worse deadlock than in the past three years,'' he says. ''With divided government, and the midterm election looming, we'll just drift along.''
But other political analysts do not see inevitable stalemate in a second term. Richard Scammon, a respected election analyst, notes that even in the first Reagan term it was possible to forge compromises on social security, foreign policy, and other issues. ''It doesn't mean there won't be fights,'' he says, ''but these will be arguments revolving around local interests and geography. The notion that there will be ideological armies in stalemate is nonsense.''
With a lot of wheeling and dealing, says Mr. Scammon, it is possible that Congress and the President can reach agreements, as they did in the case of the last tax bill.
Where the President's social agenda is concerned, however, experts believe that Reagan will continue to press for legislation but, in the face of congressional resistance, will not push very hard.
With less room for maneuver on the domestic front, many analysts see the President turning increasingly to foreign policy as the focus of his attention, just as have other second-term presidents. The common wisdom here is that Reagan wants to leave his mark on history and is therefore determined to accomplish something in arms control.
''He clearly wants to do something in terms of our relations with the Soviet Union,'' says Henry Nau, a former staff member of the National Security Council. ''It's important to him to go out as a popular President. But he has to move quickly, because by mid-1986 he's a lame duck. I wouldn't rule out his dispatching (Vice-President George) Bush to Moscow to begin a few negotiations and Reagan going to Moscow to launch them. They might never agree to anything, but it could be a dramatic spectacle in the first year.''
Just how dynamic and creative a diplomacy Reagan will conduct depends on what kind of support he commands in Congress and on whether he himself will become more engaged in policymaking than he has been in the past. The President has not evidenced much desire to shape foreign policy as did, for example, Richard Nixon.
Some experts see an uneventful four years ahead unless Reagan is tested by a Soviet or some other challenge.