President Reagan's strategy for coming out on top politically on the budget fight now is emerging.
He has embraced a compromise fiscal 1983 budget agreed to by the GOP-controlled Senate Budget Committee. And White House insiders say he is ready to adopt a ''full-court press'' to ensure the measure's passage.
The proposal provides for some $40 billion in unspecified social security savings, $22 billion in defense cuts ($5 billion the first year), and a $95 billion increase in taxes - all over the next three years.
The plan would also freeze nonmilitary programs for three years - in effect forcing reductions because the programs wouldn't keep pace with either population growth or inflation.
The compromise would leave a projected deficit of $106.1 billion for next year and - it is hoped - reduce the deficit to $39.5 billion by 1985. Experts say Mr. Reagan's original '83 budget have would produced a deficit as high as $ 132 billion the first year.
Democratic leaders in both the House and Senate rejected the proposal, charging it would slash benefits for the elderly and spending for the poor while maintaining huge defense outlays and retaining tax breaks for the rich.
Senate Democratic leader Robert C. Byrd (D) of West Virginia accused the Republicans of ''mortgaging the economic future of the elderly of this country . . . to finance the folly of the Kemp-Roth tax (cut) scheme.''
Despite Democrats' objections, observers here say the compromise - which cleared the Senate Budget Committee 11 to 9 - is likely to sail through the Senate, with changes, if any, that would be satisfactory to Senate Republicans and the President.
By backing the resolution, the President will ''take over full credit for the bill. It will become his budget. That's the way it works,'' says Sen. Bob Packwood (R) of Oregon.
The President is expected to use the three to four weeks between the time the Senate passes the proposal and the House votes on it to rally the nation behind the plan. Further, Mr. Reagan is said to be counting on economic experts and the editorial writers to see the compromise as a credible approach to reducing the budget and, hence, to reducing interest rates.
Thus, once he exerts pressure to gain House votes, particularly among Republicans and Southern Democrats, the President is said to believe he may be able to set up momentum that will make it very difficult for the House to reject either the Senate proposal or an alternative plan that could come from conference committee as substantially the Reagan-approved Senate version.
Talking with reporters over breakfast on May 6, Senator Packwood, who met with the President on the budget May 5, conceded that the House might reject the thrust of the Senate proposal. To cope with that, the President is already getting ready for a mighty confrontation with the Democrats over the budget in the fall elections, say Packwood and White House strategists.
Mr. Reagan is expected to make the case that he walked the extra mile to compromise with Speaker O'Neill and other House Democrats - but that he met with intransigence.
Above all, if the House rejects the Senate budget proposal, Reagan is expected to argue that the vote indicates the Democrats' unwillingness to deal realistically with budget problems and that Democratic foot-dragging has bogged down his efforts to try to take measures necessary to turn the economy around.
At an impromptu news conference on May 6, the President was asked, ''What if the Democrats don't pass the Senate budget plan?''
His answer was that ''it would then be very difficult'' to explain to the people why they would not accept a proposal that would reduce the budget by $416 billion over the next three years. Reagan said the Senate plan ''would continue to bring down the growth of government spending'' and would provide sufficient funds for his defense buildup.
When the President started to push the compromise with the congressional negotiators, O'Neill was quoted as saying he feared that Reagan was ''setting us up.''
By that, he said, he meant that the President might be trying to give the public the impression that he was working extremely hard for a compromise, but that the Democrats were being uncooperative - even if the facts prove otherwise.