Last March, the Republican leaders in the Senate delivered an urgent warning to President Reagan. If he couldn't get a broad and explicit agreement with both parties in Congress, they said, the budget was headed for serious trouble. His deficit was too large to pass either house. Reducing it would be sufficiently painful and risky that it could be accomplished only if everyone joined hands-- Republicans and Democrats, Congress and the president together. If that didn't happen, the senators further warned, interest rates would stay high. Then Congress would be assailed with irresistible demands for expensive bail-outs of foundering industries--and the deficit would go higher than ever.

That was good advice. Mr. Reagan chose not to follow it. You can see the consequences developing precisely as his friends in the Senate predicted.

Since the collapse of the budget negotiations at the end of April, Mr. Reagan seems to have abandoned the whole subject with a shrug. The White House says that if Congress wants to write its own budget, let it try. The administration is limiting itself to defending several of its key commitments, most notably to the succession of income tax cuts. There are now four or five budget proposals in the congressional debate, and it's fair to say that all of them are superior to the one that Mr. Reagan sent up to the Capitol last winter--superior, from the viewpoint of both the people who want lower deficits and those who want a better balance between defense and social spending.

But not to have a presidential budget before Congess, strongly supported by the administration, creates an unprecedented situation. It is hardly a good omen for rapid progress. When the administration chides Congress for delays, it is complaining, in effect, that Congress is taking too long to make the hard decisions that the White House refused to make at all in its own February budget. When it complains that Congress is taking too long, it means that Congress is taking too long to work down the huge deficit that Mr. Reagan left in the February budget that he has now abandoned.

That's one reason why you would be wiser not to count on a quick and decisive passage of a budget this summer, on the model of last summer's legislation. Another reason is that this year, Congress has to raise taxes, not cut them. How much of a raise? The congressional consensus indicates something well over $20 billion a year, at a minimum. You could say that the present stage of the budget process is the easy part. It's still all discussion of broad targets and philosophy. When that tax bill starts to move, this city's vast array of commercial and social lobbies will enter the battle and things will get truly sweaty. The temptation to push the whole business into the end of the year, after the elections, will be fierce--but no less fierce than the temptation to pass immediately all of the expensive bail-out bills for industries damaged by the interest rates.

If Congress begins to succumb to those temptations, the next fiscal year may well open next October with an even larger deficit in prospect than the $180 billion toward which present policy points. The budget process does not work well when the president walks away from it. But it's not his budget, Mr. Reagan says. It doesn't seem to be anybody's budget. And it's headed in a direction in which nobody wants to go.