Political observers in both parties said yesterday they expected a surge in President Reagan's popularity in the wake of Monday's shooting incident, but most Republicans and Democrats on Capitol Hill said they doubted it would have much impact on prospects for his economic program in Congress.

"Sympathy," said Sen. Paul Laxalt (R-Nev.), Reagan's closest friend in Congress, "is a short-term commodity on Capitol Hill."

"In the long term," said Senate Majority Leader Howard H. Baker Jr. (R-Tenn.), "the president is likely to be even more popular. That's a rule of his humor and the way he handles himself. But I don't think it's likely to have any legislative impact."

While pollsters and political figures around the country reported a wave of admiration for the courage and wit with which the 70-year-old Reagan responded to the assassination attempt that hospitalized him with a bullet wound in his side, White House officials were formulating plans for pushing Reagan's tax spending cut without Reagan.

Chief White House lobbyist Max Friedersdorf said there would be no delay in consideration of the Reagan package because of his shooting and no effort to speed up consideration to take advantage of the current wave of sympathy. "We feel we had a lot of momentum going anyway," he said.

Noting that Reagan's supporters had expected "a vigorous personal campaign by the president," beginning with speeches to at least three state legislatures this month, Laxalt said, "We have to formulate another political campaign in which we're selling a product, rather than a candidate." While surrogates can help, he said, "there's no substitute for Reagan."

Treasury Secretary Donald Regan said on ABC-TV's "Good Morning, America" yesterday that the temporary incapacitation of their leader had made the Cabinet members "determined, even more, to push his program and 'win one for the Gipper.'"

But that borrowing from Reagan's Knute Rockne movie drew mostly skeptical comments on Capitol Hill. "I can see why Secretary Regan would say that," said Rep. Barber B. Conable Jr. (N.Y.), ranking Republican on the House Ways and Means Committee and a skeptic on the president's three-year, across-the-board tax-cut plan. "But it's not as if he had been killed and somebody else where presenting the program as a personal monument, the way Lyndon Johnson did with John Kennedy's tax and civil rights bills. . . . I doubt very much it will have any effect."

Most Democrats took a similar view. A House leadership aide said "the lobbyists who are opposing Reagan's budget cuts will tuck tail for a couple of days but they'll be right back." House Democratic Whip Thomas J. Foley (Wash.) said, "The sympathy and admiration attaches to the president, but it doesn't mean that every proposal is immune from respectful criticism or comment."

As if to prove that point, the House Budget Committee session with Health and Human Services Secretary Richard S. Schweiker provided feisty questioning about a number of Reagan's budget cuts and one near-shouting match between Schweiker and Rep. George Miller (D-Calif.).

"There's a helluva difference between killing a president and wounding him in a way that does not impair his abilities," said Rep. Morris K. Udall (D-Ariz.). "There's just not the emotional impact of the Kennedy killings."

Howard Marlow, the AFL-CIO lobbyist coordinating a coalition of liberal and labor groups opposed to Reagan's proposed budget cuts, said he thought "whatever emotional impact there is will wear off in a day or two." But others expert in the ways of Congress were less certain.

Loyd Hackler, a former Lyndon Johnson aide now representing the American Retail Federation, said he had thought Reagan "was beginning to lose the real good monumentum" behind his program last week and "was in bad shape on the tax bill. . . . I think he's going to get it back because of this. . . . The members will find Ronald Reagan strengthened, and even if he can't get out there himself, conveying his wishes from the sickbed will be powerful stuff."

And Rep. Tony Coelho (Calif.), chairman of the Democratic Congressional Campaign Committee, said the wounding of Reagan means "an extension of the honeymoon by three to five months . . . and enough pressure on Republicans to go along on the tax bill that he might win that one, too."

Coelho mentioned that "there is no way the Democrats can attack Reagan at all" during his recuperation -- and that fact some quick changes of plans by the opposition party's national chairman, Charles T. Manatt. His spokesman, Robert Neuman, said Manatt would make two fund-raising speeches in the Midwest Thursday, but the National Press Club address scheduled for April 9 as "a very partisan speech . . . will be rewritten into a much more cautious exposition of the Democratic situation."

Leading pollsters were unanimous in predicting a gain in Reagan's personal popularity, but they differed on how long-lasting or significant the effect would be. Patrick Caddell, former president Carter's pollster, said "his ratings will go up some, but it's not likely to last long. He handled himself well, but he didn't solve some great problem for the people, so it's more likely to enhance his individual standing than his policy support."

Robert Teeter, a leading Republican pollster, said, "It certainly makes people feel more personally sympathetic to him and makes it harder for the Democrats to criticize him directly. A lot of his support was soft and the fact that he handled his first crisis well . . . will firm up that support. I think at the minimum it buys him more time and makes opposition harder."

William R. Hamilton, who polls for many Democrats in Congress, said the shooting probably will delay the Democratic counterattack on Reagan's economic program for another two or three months, but could have more lasting effects on Reagan's standing.

"I think he will remain popular throughout his term now, whether or not his program works," Hamilton said. "When he showed the ability to go through this with a quip, it was something the average man can understand. It probably makes him immune from ever dropping to the low level of personal popularity Carter reached."

And Udall said, "This is a long-term plus for Reagan. He has been through the fire and escaped. There is an aura there that wasn't there before."

If that is correct, then Reagan would be a stronger candidate for reelection because of the shooting. But whether the attempt on his life and its still uncertain medical effects would increase Reagan's and his family's reluctance to see him seek a second term at age 73 was unknown.