President Reagan let it be known last week that he welcomed efforts by Senate Republican leaders to come up with their own budget plan even before the administration presents its 1986 budget early in February. He would also like Congress to get behind some version of his administration's tax overhaul plan before he decides to endorse it himself.

Most recent presidents would have been outraged if Congress had so much as implied that it wasn't worthwhile to see what the president had in mind before considering budget blueprints of its own. And other presidents certainly wouldn't have appreciated Congress' mucking around with their major reform initiatives before they had even signed off on them. But Reagan is an affable man and not one to let formalities get in the way of his convenience.

In fact, it's fair to say that not since Tom Sawyer has anyone been as adept at getting other people to do his dirty work for him. Like Tom, moreover, the president has been able to accomplish such delegations not only without loss of face, but with positive improvement of his reputation for leadership and accomplishment.

This is, after all, the fourth year in a row that Congress has had to take the lead in shaping spending and taxes. Only in 1981, his first year in office, did Reagan dominate congressional action when he pushed through the big tax cut and military budget increases that had so much to do with today's massive deficit. In each of the subsequent three years the administration has gone through the motions of preparing budgets calling for severe cuts in social programs but leaving still enormous deficits. These were duly forwarded to the Hill where, after a delay of some months, they were discarded in favor of more realistic plans. The difference this year is that Congress is of a mind to dispense with even the formalities of considering the president's plans.

This may be momentarily embarrassing to the president, but consider the alternative. Having heaped scorn upon his campaign opponent for suggesting that tax boosts and restraints on military spending would be needed to narrow the deficit, and having stoutly denied that he had any plans to restrain Social Security benefits, the president can hardly lead the charge on these issues so soon after his massive victory. And when Reagan, at the urging of Budget Director David Stockman, began to study the deep cuts in other domestic programs that would be needed to make a noticeable dent in the deficit, it is easy to imagine that he felt much as Tom Sawyer felt viewing 30 yards of board fence: "All gladness left him and a deep melancholy settled upon his spirit."

True, the president seemed inclined initially to go along with Stockman's budget- cutting plans. But his reluctance has apparently grown as his Cabinet secretaries have appealed OMB's decisions, pointing out their unpleasant political, social and economic consequences. Freezing food stamps and welfare for the aged and disabled, for example, didn't seem like such a good idea after the health and human services secretary pointed out how unfair it was to force the poorest of the poor to absorb the costs of inflation while protecting higher income Social Security recipients. And shifting to states still more of the burden of medical care of the indigent was a less attractive idea after many governors let the White House know their opinions on the matter.

Still stronger objections have come from the president's most ardent "supply-side" supporters. Congressmen such as Jack Kemp, Trent Lott and Newt Gingrich have complained that OMB's harsh-sounding cuts are not required by their philosophy and make it harder to build support for a "Conservative Opportunity Society" of the future.

Why underwrite all this suffering if all you have to show for it is a small dent in a budget deficit that grows larger with each recalculation? Why not leave the hard choices to Congress? No matter what the outcome -- continued big deficits, big tax boosts or big spending cuts -- most people will be unhappy. This way the president can join in the chorus of criticism no matter what the refrain.

This deference to Congress doesn't mean that the president has lost interest in the budget. He has been, after all, a persistent deplorer of the dangers of deficit-spending throughout his political career. Just as Tom Sawyer warned his surrogates that Aunt Polly was mighty particular about how the whitewash was put on her fence, so Reagan will want to remind congressional leaders of his own strong feelings about dealing with the deficit.

Thus Reagan will continue to insist -- as he did at his Wednesday press conference -- that deficit reduction must come through cuts in social spending rather than through restraining the Pentagon's budget or raising taxes. And he will go on insisting this until such time as Congress -- both the Republican Senate and the Democratic House -- have finally persuaded him (against his better judgment, he may suggest, when it suits his purposes) that they are willing to take the heat for the unpopular necessities that narrowing the budget deficit will inevitably entail.

What a dumb way to lead the country. Dumb like a fox.