House Speaker Jim Wright (D-Tex.) plunged ahead with his version of a peace plan for Central America despite vocal and virtually unanimous opposition by the handful of other House Democratic leaders he consulted, congressional sources said yesterday.

Wright initially planned to unveil the proposal in a speech here last week but was persuaded that this would only increase risks to him and his party should the proposal fail, they said.

"We tried to slow him down," said a House Democrat familiar with the two weeks of intense negotiations preceding formal announcement yesterday of the initiative.

Most House Democrats appeared to be falling in behind their leader yesterday. Skepticism about the Reagan administration's intentions remained high, but private opposition to the plan did not surface publicly as Democrats expressed a sense of resignation.

"The feeling is that it is a done deal and what can we do," one House Democrat said.

In secretly negotiating with senior administration officials, House Republican leaders and officials of several Central American governments, including Nicaraguan Ambassador Carlos Tunnermann, Wright in effect preempted his House Democrats, the vast majority of whom learned of the proposal from news reports.

It was another example of his leadership style, which contrasts sharply with that of his predecessor, Thomas P. (Tip) O'Neill Jr. (D-Mass.).

Wright first displayed that style on the day he was chosen to succeed O'Neill last December. He publicly suggested support for a tax increase to reduce the federal deficit. O'Neill, concerned about political consequences for Democrats, had ruled out talk of higher taxes unless President Reagan made the first move in that direction.

Wright again appeared to have put himself far ahead of most other Democrats. Were O'Neill still speaker, one Democrat said, he would say "we've got the votes" to defeat more aid to the Nicaraguan contras, "so make the administration come to us to make a deal."

Wright, however, voted for contra aid early in the administration and has never been as vehement as O'Neill in opposing administration policy in Central America. "He truly believes in a bipartisan foreign policy," said Rep. Dave McCurdy (D-Okla.), a moderate who has led efforts to reach a consensus on that policy.

A Democratic aide also noted that Wright, who comes from a part of the country where contra support is stronger than elsewhere, calculated that, for Democrats to stick with an all-out anticontra policy "is not necessarily politically safe for a lot of Democrats in the South and Southwest."

The initiative embraced by Reagan was set in motion July 22 when former representative Tom Loeffler (R-Tex.), a White House strategist on contra aid, suggested to Wright that he work with the administration in devising a bipartisan approach.

According to Democratic sources, the discussions initially were confined to a few House members, including Majority Leader Thomas S. Foley (D-Wash.), Majority Whip Tony Coelho (D-Calif.) and Rep. David E. Bonior (D-Mich.), a leading contra-aid opponent. Wright also consulted from the beginning with House Minority Leader Robert H. Michel (Ill.) and Minority Whip Trent Lott (Miss.).

The sources said the Democrats objected strongly, expressing concern that Loeffler's proposal was "a deliberate plan to deceive the speaker" and "trap him" into supporting more contra aid after the initiative failed.

Wright listened, they said, but replied that, while he did not trust Reagan, he was convinced of the sincerity of administration officials with whom he was dealing -- Loeffler, Secretary of State George P. Shultz and White House chief of staff Howard H. Baker Jr.

One congressional source quoted Wright as saying:

"Look, I'm the speaker of the House, and they're saying they want peace. What am I supposed to do, walk away from that?"

Last Thursday, according to the sources, Wright was persuaded to share the proposal with more House Democrats, including several contra-aid opponents. "Basically, it was to let him know just how bad the skepticism was," one source said. "But he was already personally committed." That night, Wright visited Senate Majority Leader Robert C. Byrd (D-W.Va.) at his home, sharing the plan for the first time with his Senate counterpart.

Opposition remained strong Tuesday when Wright outlined it to about 35 House Democrats. Only a few voiced support.

"I think we're getting set up," a Democratic aide said after learning of the Tuesday meeting.

By yesterday, when virtually the same group of Democrats met with Wright, the mood had shifted to warnings that, because he had committed Democrats to the plan, they must be sure that the administration kept its part of the bargain.

"If the administration thinks they have him locked up so that if it fails they get contra aid, then it will fail," Rep. Barney Frank (D-Mass.) said. "We told the speaker the plan is much more likely to succeed if you are independent of it."

Throughout the day, Wright appeared serene about what was repeatedly described as the "high risk" road he had chosen. He said at the White House that House Democrats are "not going to rebel against me," and Frank said that "people think he did it for the right reasons -- to stop the killing."

McCurdy said, "You've got to applaud Jim Wright for being willing to stick his neck out and keep his eye on the real objective, which is peace in the region. He's demonstrating that he's the leader. At least he's willing to pick out a hill and go up it."

But McCurdy, summarizing potential risks and rewards for Wright and his administration negotiating partners, added:

"It's one thing for someone in the White House to lie to me, and another thing to lie to the speaker of the House. Of course, it's also one thing for me to stick my neck out and another for the speaker to do it."