President Reagan last night submitted a report to Congress that triggers a vote later this month on his request for aid to antigovernment rebels in Nicaragua and, sources said, today intends to unveil a new plan for "reaching a peaceful conclusion" to the Nicaraguan conflict.

The report was required last year as a condition for release of $14 million in funds for the Central Intelligence Agency to help the "contras" fighting the Sandinista regime.

However, an administration official said Reagan "has a peace plan in mind" that is "a great deal more than a request for Congress to let him spend $14 million on paramilitary forces in Nicaragua."

Reagan is expected to detail the plan today after meeting Colombian President Belisario Betancur at the White House.

Betancur arrived here after visiting the heads of state of nine nations involved in current Central American peace talks.

The decision to submit the report to Congress came late yesterday as Reagan's senior advisers were reported to be divided over how to proceed.

Sources said White House chief of staff Donald T. Regan and national security affairs adviser Robert C. McFarlane were initially reluctant to press Congress now for additional aid to the contras, given gloomy prospects for approval.

Communications director Patrick J. Buchanan and departing public liaison director Faith Ryan Whittlesey were pushing for quick action on the issue, sources said.

An administration official said last night that the peace initiative originated late yesterday with McFarlane, who took it to Reagan. The president said he was interested in the idea and gave his approval for McFarlane to consult with key members of Congress about it, the official said.

The process triggered by the report will probably result in a congressional vote on Reagan's request between April 17 and 24, just after Congress returns from Easter recess, sources said.

Reagan plans to return here April 14 after a scheduled 10-day vacation at his California ranch.

Yesterday afternoon, the White House began consulting with key members of Congress on the Reagan peace plan, providing "broad outlines" but no details, one official said. Reagan was in the "final stages of deciding" on the details, the official said.

The plan emerged after a morning meeting with the Republican congressional leadership in which the president was told that prospects were not good for his previous proposal for channeling direct covert aid to the contras through the CIA.

House Minority Leader Robert H. Michel (R-Ill.) said he told Reagan that the proposal was "dead in the water" and urged the president to show some flexibility.

Senate Majority Leader Robert J. Dole (R-Kan.) also indicated that he would prefer to delay debate on Nicaragua until after the Senate considers a deficit-reduction package.

Rep. Michael D. Barnes (D-Md.), chairman of the House Foreign Affairs subcommittee on Western Hemisphere affairs, said last night that he is "very surprised" by Reagan's move. He said critics of direct aid to the contras have an advantage of 20 to 30 votes in the House, and added, "I have not seen any erosion in that vote."

Rep. William F. Broomfield (R-Mich.), ranking minority member of the House Foreign Affairs Committee, said he was notified of the president's action late yesterday but could not reveal the details. He said the new plan could alter the vote count in the House.

"Reagan's track record is pretty good," he said.

After meeting with Reagan, Michel said of the contra aid: "I wanted the administration to fully understand that, without any change in formulation of policy there, we are dead in the water for the moment in the House of Representatives."

"We have got to have some flex and a little bit of movement there to get us what we eventually would like to get," Michel told reporters. "I want to see something fly, and we can't put our fingers yet on exactly what that might be."

He said some House Democrats have changed their thinking on the issue, but he did not identify them.

Congress last year blocked the administration from sending $14 million in covert assistance to the contras.

In recent speeches, Reagan has described the contras as "freedom fighters" and "our brothers" as he increased rhetorical pressure on Congress to release the aid.

Some administration officials have said the president would wage an active campaign for aid to the contras, including a possible speech at the Orange Bowl in Miami or on national television.

Reagan has said he will not be deterred from seeking aid to the rebels but suggested in an interview Monday with reporters for The Washington Post that, if Congress continues to block the aid, there are other means of helping them, including support from private groups.