President Reagan told congressional leaders yesterday that he would seek $36.25 million in aid for the rebels fighting the Marxist government in Nicaragua, including $3.6 million in military aid that would be placed in a separate account, administration officials said.

The military aid would be held in escrow until it is determined whether Nicaragua complies with the peace process all five Central American presidents agreed to last August. Administration officials wrestled into the night searching for a congressionally acceptable formula that would establish when military aid should be released.

The scaling down of the aid request, which Reagan will submit to Congress today, and the placing of lethal aid in an escrow account was designed to win the support of swing voters in the House, mostly moderate Democrats who favor providing the contras with food and other supplies but oppose further military assistance to them.

House Democratic leaders denounced the new proposal as "cynical," but White House officials and some House Republicans said the plan might enable the administration to eke out a victory when the House votes on the package on Feb. 3. Others questioned whether the tiny military aid request was more than symbolic.

Rep. Lawrence J. Smith (D-Fla.), who joined about 20 other Democratic moderates in signing a recent letter asking Reagan to delay his aid request, said he would be "inclined to vote" for the new package.

But he mocked the administration, which has so pared the military component that it is almost meaningless. "It's a sexual fantasy with them," said Smith. "Without military aid it's not a satisfying experience."

But by last night White House officials had been unable to come up with a formula for releasing the military aid that they thought would satisfy Congress.

The administration was described early in the day as favoring a plan that would require another congressional vote in April before any military aid could be delivered to the contras. But there were objections, both at the White House and on Capitol Hill, that the plan smacks of a "legislative veto" of the kind Reagan has repeatedly opposed.

Another possible trigger mechanism would make delivery of the military aid contingent on approval of the four Central American governments that joined last August with Nicaragua in signing a regional peace accord. A senior White House official said that a final decision on this part of the package would not be made until this morning.

Rep. David E. Bonior (D-Mich.), who heads a House Democratic leadership task force on the issue, said the administration request represents a "serious escalation of the war" and a "ruse" to capture votes. "My guess is it would be extremely, extremely difficult for the president to get the votes," he added. "We are very close to defeating this kind of package."

Rep. Dave McCurdy (D-Okla.), the author of the letter asking Reagan to postpone his request, said that even with a certification trigger in the hands of Congress, "with military aid in there it will not pass {the House}."

Some Republican supporters of the proposal said, however, that Reagan may have found the right formula for getting the aid package through the sharply divided House, where both sides have won narrow victories in the past.

"It's a good package, carefully crafted by the administration to be supportive of the peace process, and I think our prospects to pass it have been significantly improved," said Rep. Richard B. Cheney (R-Wyo.), a member of the Republican leadership. "If you can sell anything, you call sell that package," said Rep. Mickey Edwards (R-Okla.). "It's very reasonable."

The White House has been leaning to an escrow-account approach to contra aid for several days, but the president has been reluctant to give Congress control over release of the funds. The idea of a "legislative veto" and a second vote on the military aid aspect of the package gained support at the White House yesterday morning after a bipartisan group of six senators told Reagan that this approach had a chance of winning the support of House Speaker Jim Wright (D-Tex.), sources said.

But Wright aide Wilson Morris said late in the day that the speaker would consider an escrow arrangement only if it is "consistent with the Central American peace process" and left verification of a cease-fire up to the region's presidents.

Reagan will make his formal case for additional contra aid, which he contends is necessary to keep pressure on the Sandinista government in Nicaragua, in a speech today to the Reserve Officers Association. He is expected to say that if Congress approves the aid package, he will send Secretary of State George P. Shultz to Central America to meet with regional leaders, including Nicaraguan representatives, in an effort to accelerate the peace process.

State Department officials said Reagan will recall that in a Nov. 9 speech here to the Organization of American States he said that the United States would resume security talks in "a regional context" involving all five Central American nations in the peace plan if the Sandinistas negotiate with the contras. The other nations are Costa Rica, Honduras, El Salvador and Guatemala.

Reagan is expected to say that a Shultz visit could contribute to a diplomatic solution. But the officials said Reagan will stress that for such an effort to be successful, Congress must "give Shultz the tools" such as continued contra funding.

The president repeatedly has rejected bilateral U.S.-Nicaraguan talks that Nicaraguan President Daniel Ortega has requested. The United States has not had any direct, high-level talks with Nicaragua since late 1984 when the administration cut off a series of periodic meetings in Manzanillo, Mexico, on grounds the Sandinistas were using them to obstruct regional peace negotiations. Staff writers Bill McAllister and John M. Goshko contributed to this report.