Bipartisanship yields to election mood as Congress faces tough tax-or-trim decisions

The bipartisan spirit that produced major legislation earlier this year is showing signs of strain as the 98th Congress takes off for the Memorial Day break.

''Congress isn't going to do much till after the (November 1984) election,'' Sen. Robert Dole (R) of Kansas predicted recently. ''I don't think we're going to do much till '85.''

Within its first three months, the new Congress bolted out of the starting gate, passing major social-security reform and a recession-relief bill. It did both with the cooperation of Democrats and Republicans and the aid of a conciliatory President Reagan.

In fact, that spirit of cooperation goes back as far as last year, when the White House and leaders of both parties joined forces to pass a $99 billion tax bill and later a 5-cent-a-gallon tax on gasoline.

Now a new mood is apparent on Capitol Hill. Most of the legislation on which there is broad public and political agreement is out of the way, and the lawmakers are facing the tough ones.

They are looking at a proposed '84 federal budget with nearly $200 billion in deficits. The budget will go to a House-Senate conference early next month, and the leading participants from both parties and houses have only one firm agreement: ''The issues facing us in conference are formidable,'' they said recently in a joint statement.

To come up with a federal budget, they will have to pick between the unpopular idea of raising taxes and the equally unsavory plan of cutting spending, or else bear the embarrassment of approving so much red ink.

Overshadowing their deliberations are the 1984 elections, as Congress and the White House begin laying the groundwork for political campaigns. Budgets, taxes , and almost every other issue on Capitol Hill are being viewed at least partly through the lens of politics.

Both Democrats and Republicans on Capitol Hill point to the President as the one who ''threw the first ball'' of the political game. He refused to compromise on his requested 10 percent after-inflation defense increase, even when he saw that neither house would buy it.

When the Senate passed a budget with more taxes and domestic spending than he wanted, he sent a message that he would veto any tax hike or any spending bill he found inflationary.

Mr. Reagan appears to have set the stage for confrontation on domestic issues , not only with Democrats but with all of Congress, which has been increasingly independent.

Meanwhile, Democrats have been no less political during the budget battle. The House-passed version, clearly labeled a ''Democratic'' budget, is a direct slap at the President's economic program.It would attempt to overturn the past two years of Reaganomics and take back the 10 percent income-tax cut scheduled for next July.

In the Senate, meanwhile, restless Republicans are no longer willing to toe the presidential line, especially since many represent Northeast states with high unemployment.

Moderate GOP members, who bit their tongues for nearly two years, stood firm during the recent budget debate on the Senate floor. They had enough votes to force passage of a bipartisan compromise budget with more taxes and spending than Reagan requested.

''What's new is that the Senate will not go along with the President, and the President has to adjust,'' says a senior House aide.

But as the aide concedes, Reagan has not lost all of his bipartisan appeal on Capitol Hill, especially in national-security matters. ''The MX is a boost to the President,'' he says of votes in both the Democratic House and GOP Senate this week to proceed with deployment of the missile.

''On the other hand, the only reason he was able to win was because he was willing to make fundamental changes in his arms control policy,'' according to the aide, citing the President's promise to be more flexible in his approach to arms control.

Another test of bipartisanship will be over Central America policy. While a president's foreign policy has almost always been supported by both parties, Democrats have sharply criticized the Reagan policy on El Salvador and Nicaragua.

However, while Democrats have recently reached out to Republicans in an attempt to build a consensus, they have not yet thwarted the Reagan administration in Central America. If they do move in this policy area, it will almost certainly be with caution.