Washington — With the election of the new Congress, the days when Republicans along with their Democratic allies marched lockstep behind the President are clearly over.
For almost two years, the ''Reagan revolution'' encountered only token resistance on Capitol Hill. In quick succession, Mr. Reagan won spending cutbacks in domestic programs, the biggest-ever income-reduction, and a massive defense buildup.
The 98th Congress, which opens early next year, will be a less pliable group than the one that passed those measures. The Senate will be much the same, but the House will be far more Democratic, and those Republicans representatives remaining will be more independent of the President.
''You sure as heck can't look at it like the last two years,'' said minority leader Robert H. Michel of Illinois in a telephone interview from Peoria, where he narrowly won the toughest campaign of his 26-year career.
Looking at the new lineup of 166 Republicans to 269 Democrats, he said, ''You tell me how you fashion a coalition with that big of a disparity.'' During the past two years, Mr. Michel and about 30 conservative Democrats forged a coalition that held the balance of power in the House. Now he would need about 50 or 60 Democrats, while holding all of his own members.
''We're back to the days when we've got to scrap for everything,'' Michel said.
With the loss of 26 Republican incumbents, including many who had voted faithfully with the President, Michel will be keeping a wary eye on protecting his members in the future. ''I want to have input with the administration so they don't have members hanging out there to dry,'' he said.
Few observers see the election last week as a rejection of President Reagan.
''It is a slight swing to the left within the center,'' veteran political observer Richard Scammon told reporters over breakfast last week. ''The center is always dominant in American politics,'' he says, calling the election a ''corrective'' action following the conservative victories of 1980.
But the question is whether the swing to the middle ground will enable the new Congress to act. It will face the most difficult economic times and joblessness since the 1930s, a social security system that is running short of cash, and the biggest federal deficit ever.
At the same time, the government is now more clearly divided. The newly strengthened and slightly more liberal Democrats now have a firm grip on the House, while the Republicans control the Senate. At the White House, Mr. Reagan gives no hint that he will compromise. Added to these problems will be the likelihood of party grandstanding for the '84 presidential elections.
As a result, political scientist Scammon predicts it will be ''a relatively noisy Congress and a relatively inactive one.'' Still, Congress will be pressured to act in several areas:
Jobs. Both parties will be pushing for action. Rep. Tony Coelho, of California, chairman of the Democratic Congressional Campaign Committee, says federally financed jobs and housing programs will be on top of the agenda.
Even minority leader Michel, a staunch opponent of ''make work'' projects, talks about a possible jobs program. ''I'm not going to turn around on my personal philosophy after 26 years,'' he says. ''But if (the economy) is flat in spring, then we've got to think in terms of how do you give it a starting shot. . . . '' That could even include a public-works program for areas with high unemployment, says Michel.
Social security. One of the hottest issues during the campaign, social security reform has yet to cool off enough for the lawmakers to handle. A bipartisan commission is due to release a report soon on how to make the system solvent, but commission member Sen. Robert Dole (R) of Kansas and House speaker Thomas P. O'Neill Jr. (D) of Massachusetts are already quarrelling over whether the commission should issue findings.
All hopes that the lame-duck session of the current Congress, scheduled to begin after Thanksgiving, would reform social security have been dashed. In fact, it now seems unlikely that any major changes will be made in the system even after the new Congress takes office. One possibility, mentioned by some new House members, is paying benefits out of general revenues should the system run out of money.
Budget. Reducing record-high federal deficits will be the focus as the new Congress works on the '84 budget, which the White House will deliver early next year. It could produce the first major test votes in the new Congress, where many members will attack the White House-backed military budget. Meanwhile, the House will almost certainly resist further cuts in domestic spending.
Taxes. Democrats will probably attack the planned 10 percent income-tax cut for July 1983, while President Reagan can be expected to resist any move to alter it. Proposals range from eliminating the cut altogether to giving it only to low- and middle-income taxpayers.
Social issues. Highly emotional issues such as abortion bans and school prayer may come up in the coming session. But they are not likely to hold center stage. Congressman Coelho points to North Carolina races in which Republicans campaigned heavily on those issues - and lost. ''The issues today, '' he says, ''are not the New Right issues. They're the economic issues.''