Democrats want President Reagan to take the first step. Reagan is resisting. Republicans need the Democrats, but the Democrats won't move without Reagan. Congress waits for Reagan; Reagan waits for Congress.

Alphonse and Gaston would feel right at home.

The congressional search for a bipartisan alternative to Reagan's high-deficit budget may not have reached an impasse, as House Budget Committee Chairman James R. Jones (D-Okla.) has suggested. But it has yet to get around the obstacle that has stood in its way from the start: a distaste for political martyrdom at both ends of Pennsylvania Avenue.

It is not hard to find keys that might open the door to negotiations and eventual compromise. The problem is that all the choices entail big political risks, and each side has reason to fear the repercussions.

Reagan has staked a lot of political capital on his economic program and the argument that--given enough time--it will work. Therefore, he is reluctant to give any ground before he is forced to do so.

But Congress, with the November elections facing the entire House and one-third of the Senate, is choking on the huge deficits in his budget. While Republicans have taken the lead in trying to cut the deficits, the conservative coalition that prevailed last year when Reagan was stronger in the polls has crumbled, and Republicans need the support of Democratic leaders to make politically difficult spending cuts and tax increases.

Democrats say they are willing to go out on a limb with the Republicans--but only if Reagan goes out with them. Recalling how Reagan chose political victory over bipartisan cooperation last year, they fear he will saw off any limb that he isn't on.

Reagan responds that he will consider any genuine, comprehensive bipartisan alternative that Congress produces, but, so far at least, he's not giving any ground in advance.

Social Security illustrates the problem.

Reagan could signal that he's willing to consider cuts in cost-of-living adjustments for Social Security, which would clear the way for Senate Republicans to move on a set of options that could get the budget deficit down to $20 billion by 1985--no mean achievement in light of the annual deficits of more than $100 billion that may occur otherwise.

But Reagan has been burned repeatedly on Social Security, most recently last year when he proposed a long list of Social Security cuts, including a delay in inflation adjustments. It was unanimously rejected by the GOP-controlled Senate, and the Democrats spent the rest of the year making political hay out of the issue.

Another possibility would be for the Democrats to take the lead on Social Security and other major benefit programs, which even many Democrats agree--often privately--have to be curtailed if deficits are ever going to be brought under control.

But Social Security and other social programs are political meat and potatoes to most Democrats. Thanks to Reagan, Social Security was one of the few issues they had last year and they are naturally reluctant to give it up, although a group of moderate Democrats on the House Budget Committee has dredged up the courage to suggest cost-of-living increase limitations as a possible option.

Senate Republicans have brought up Social Security inflation adjustments, in a very gingerly way--only to be shot down almost daily by the White House. They still are trying, but they concede they need more encouragement than they are getting now.

Then there is the matter of taxes.

Reagan has made his big individual tax cuts the linchpin of his economic recovery program and has adamantly refused to yield on them, making it difficult if not impossible for Republicans to tap the single biggest potential source of deficit reductions.

Many Democrats, including the entire Senate Democratic minority, are suggesting deferral of the scheduled 10 percent tax cut for 1983, along with a delay of tax rate indexing which is scheduled to begin automatically lowering tax rates to account for the effects of inflation.

But that doesn't much help the Republicans, who are looking to the Democrats for a willingness to cut spending as a bargaining chip to convince Reagan to negotiate on taxes. Only if Congress demonstrates a bipartisan willingness to cut spending will Reagan yield on taxes, some Republicans have suggested.

Many Republicans still contend that Reagan, if presented with a good congressional package, eventually will bend on taxes as well as other "off limits" items such as defense and Social Security. But, on taxes at least, Reagan has been moving publicly in the opposite direction, framing his version of the budget debate as a fight between tax-cutters and tax-raisers.

For the time being, congressional Republicans are left with an assortment of "loophole" closing measures. If a debate began on those measures, almost every lobby in town would be activated.

On defense, there is something bordering on a bipartisan consensus that Reagan's military buildup is too costly, and that economies can be achieved without risk to national security. But, because so much spending already has been locked in by earlier procurement commitments, it is hard to find big immediate savings without touching the "untouchable" of military readiness, many argue. Moreover, Reagan has made defense a flag-waving issue that could become scary for politicians nervous about reelection.

So far all Congress has decided is that it doesn't like Reagan's proposed deficit reductions, many of which hit hard at programs that were cut deeply last year. Committee after committee has rejected most of his spending cuts, in the Republican Senate as well as the Democratic House.

So what happens next?

The congressional Republican strategy appears to be to grasp any opportunity, especially one that might get Reagan to consider compromise.

Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) has developed options with his fiscal committee chairmen and started talks with their Democratic counterparts. House Minority Leader Robert H. Michel (R-Ill.) is trying to convince Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) to come to the table with House Republicans, although O'Neill has said he would rather go to Camp David with Reagan.

Jones, the House budget chairman, is talking about forcing a vote on Reagan's budget, but that seems to conjur up fears of a Frankenstein's monster among many Democrats as well as Republicans. Some House Budget Committee Republicans have started shipping ideas to the White House, which has received so many such ideas that aides have said they are being kept in loose-leafed binders.

Baker and others assert that Reagan eventually will come to terms with Congress. But there is no guarantee. Some fear that Reagan may be holding out in hopes of both a congressional stalemate and an economic upturn, coupled with lower interest rates, that would ease pressure for deficit reductions.

If nothing happens by the time Congress has to extend the federal debt ceiling, probably around mid-May, the crunch may have arrived. Republican leaders figure they need big deficit reductions to offset the bitter taste of a debt limit increase, which is needed to keep the government operating on borrowed money.

At this point, some Democrats hold out one final option: a declaration of independence by congressional Republicans, especially Baker, to ignore Reagan and cut a deal with the Democrats. But Baker has said repeatedly he won't do that. "That is not an option as far as Howard Baker is concerned," said an aide last week.

Failure to pass the debt bill would mean suspending government operations for lack of borrowing power. Last year Reagan and Congress closed the government for a day, then compromised on budget cuts. But there is no guarantee this year that such a compromise would mean a budget with the kind of deficit reductions that Congress wants.

The result, some say, could be collapse of the already strained congressional budget control process and "government by continuing resolution," meaning periodic extensions of existing spending authority.

Out of such chaos could come the very kind of runaway deficits that both Congress and Reagan are pledged to avoid.