Washington — The feeling in the spring air here is not unlike that which preceded the election last fall: A Reagan victory seems almost certain. This time the Reagan triumph will involve getting the votes of every Republican in the House plus at least 26 Democrats in order to win the first major congressional test of his economic plan.
The anticipated outcome in the House -- to be followed, it appears, by a relatively easy win in the Senate -- will be influenced by these elements:
* Above everything else, the President's overwhelming popularity is persuading Democrats to side with Mr. Reagan, even though many of them are convinced that his three-year tax-cut proposal is unacceptable.
In fact, it is conservative Democrats who entertain reservations about Reagan's tax policies but not about his slashes in spending who, for the most part, are coming over to give the President the numbers he needs for a victory in the impending vote.
For tactical reasons the President has adopted a compromise budget that stems from these Democratic congressmen.
But the fact is that these Democrats have moved toward the President's position and not the other way around.
Observers are saying that there isn't more than a "dime's difference" -- not much more, anyway -- between the President's budget proposal and the compromise.
* Many Democrats appear to be caving in to the President. This is evidenced by the actions of many liberal Democrats who although planning to vote against the Reagan budget simply are not putting up much of a fight.
These liberal Democrats in both Houses are speaking softly because, as they will tell you, they feel they are carrying a rather small stick.
They don't see how they can successfully oppose the President when he can pull a favorable poll rating, as he did after his recent speech to Congress, of upward of 80 percent.
But there are liberals among congressional critics who are charging their representatives here with being remiss in not putting up more of a battle.
They say it is time for Democrats who are unhappy with the way the Reagan spending cuts will tear into humanitarian social programs to raise their voices in anger.
They say that if this dissent does not come now, it may be too late to be effective when the spending-reduction proposals are considered separately.
Much of this discontent is centered on Speaker of the House Thomas P. O'Neill Jr. (D) of Massachusetts, the "old liberal" who in the past helped lead the charge in getting social legislation enacted.
* The President has been particularly persuasive in using personal politics to influence the budget vote.
He has brought his charm to bear on about 40 House members, almost all of them Democrats.
He has called them in to the White House individually for little "chats." Those involved have afterward described Reagan's approach as being more to give "suggestions" than to engage in presidential arm-twisting.
The "suggestions" expressed gently by the President, it seems, are that it not only would be doing the "right" thing to support the Reagan budget, but that voters back home also would be pleased to see their congressman backing the effort to reduce big government and big spending.
The President leaves the implication -- so it is reported -- that voters might be just a teeny-weeny bit displeased if their congressman voted the "wrong" way on this issue --enough so as to show this unhappiness the next time they cast a vote.