Washington — Americans watching President Reagan negotiate with Congress over the budget this spring may think Washington is caught in slow motion.
Neither the White House nor the Democrats are in any hurry to strike a deal, despite the waving of red flags in public over deficits, interest rates, recession, and lost jobs.
Among the flag wavers are moderate Republicans, especially senators who see their hold on the upper chamber threatened unless a reasonable pact is forged quickly.
Unless some precipitating event occurs -- a steep drop in the President's approval rating or an alarming extension of the economic doldrums into the summer, or both -- Mr. Reagan will likely stand pat on his program and wait for Congress to come to him with a compromise budget. ''We think a consensus will emerge on the Hill and move closer to the President,'' White House spokesman David Gergen told reporters at a breakfast March 2.
Hill Democrats acknowledge this as the Reagan strategy. They are not counting on being able to pin the loss of a major House vote on the President to show an erosion of his power. They failed to beat the President in three such votes last year, and they see him avoiding the risk in 1982. They are already looking past summer to the fall election.
''The final accounting for Reaganomics will be the November election,'' says a spokesman for House Speaker Thomas P. O'Neill Jr. (D) of Massachusetts.
''The assumption of the Democratic leadership all along is that the 1982 congressional elections will be of the same nature and character of all the elections since 1976 -- and possibly '74 -- namely, a referendum on the economy. The economy is his economy.''
The Washington political outlook, then, is for possibly no climactic event in coming months. The administration will be hoping an economic upturn will vindicate their policies, and the Democrats will hope public disenchantment with Republican rule will help them at the polls this fall.
Meanwhile, Reagan's popularity is declining, but not yet at a precipitous rate.
Since the first of the year, pollster Louis Harris has recorded a turn from a positive to a negative rating for President Reagan. In early January, 52 percent of the public rated Reagan's performance excellent or pretty good in Harris's surveys, 47 percent only fair or poor. In mid-February, Reagan scored 44 percent excellent-good, 56 percent fair-poor -- a 17 point swing.
Gallup's readings have had Reagan holding steadily at the sub-50 percent level for his handling of the presidency, with a continuing 70 percent rating for his personal popularity.
The broader pattern for Reagan is a slow downturn toward a negative rating, as has happened with other recent presidents during their second year, say opinion experts.
''To have a negative rating is not hopeless,'' cautions Burns Roper, president of the Roper Organization. He says he anticipates his firm's next rating of Reagan to show a majority of negative responses. ''We're getting into the situation where the yardstick is perfection, rather than 'What's the alternative?' It's now 'Reagan vs. what I'd like to see as the president,' not 'Reagan vs. Kennedy' or 'Reagan vs. Carter,' or 'Reagan vs. Mondale.' Reagan's going to be increasingly in this situation until two years from now, when he will again be measured not against the ideal, but against the alternative.''
Reagan's personal popularity and the public's willingness to give a new president more time still provide a cushion for him against criticism, even Democrats agree.
Eventually, however, the personal goodwill cushion hardens, say the pollsters. By his third or fourth year, they say, the President -- like his party in the midyear election -- is at the mercy of his record.
President Carter's third year is an example, says Paul Maslin, of Cambridge Survey Research. The polling firm monitored public opinion for Mr. Carter's campaigns and during his presidency.
''Our findings the first years of Carter's administration showed an even wider gap with Carter (than with Reagan) between his personal popularity and his job rating, as the latter started to dip,'' Mr. Maslin says. ''The voter's attitude that somehow (he) . . . promised things (he) didn't deliver, starts to prey upon a president's personal rating eventually.''
''Reagan has some personality strengths that Carter didn't,'' Maslin observes. ''Reagan has a clearer notion of what he's doing, where he's going, what he's trying to make his presidency do than did Jimmy Carter. On the other hand, he has weaknesses Carter didn't have: You have Ronald Reagan the uncaring person, the person who's siding with the rich and the wealthy. This is a personal weakness, not just a policy weakness.''