Washington is awash in hope and suspicion. Is the bird that is suddenly flying over the city a dove or a decoy?

Democrats on both sides of the question have trouble believing that President Reagan has undergone what for him had to be a religious conversion on the subject of contra aid. They are desperately trying to read his mind. Did the hearings, which he says he watched only intermittently, leave him abashed and ashamed at the sleaziness and lawlessness of his covert war? Or did their inconclusive ending persuade him that Congress is so gullible that he could, one more time, stage a peace offensive on the eve of a contra vote?

Democrats find themselves required to say for the record that they support the all but incredible Reagan initiative. They have no trouble with its contents, which seem logical and doable. The question is: Are they for real?

They remember what happened before when peace was at hand. Thomas O. Enders, assistant secretary of state for inter-American affairs, came close to making an agreement. Soon afterward, he was forced out. Philip C. Habib was sent down in July 1986, to do -- he thought -- a treaty. When he came back, Elliott Abrams, the fierce and combative present inter-American affairs honcho, held a briefing under the cloak of "senior administration official" and stabbed Habib in the back.

It is a sad history, and Democrats fear they are being set up as of old.

Is Reagan making nice because he knows that the House, which is organized down to the pages, has the votes to beat him on the $150 million in military aid? Is there some built-in catch guaranteed to show the Sandinistas are incorrigible -- and ensure the passage of contra aid? Was the new plan designed to preempt the regional peace conference being held this week in Guatemala among the four neighbor democracies, El Salvador, Guatemala, Costa Rica, Honduras, with Nicaragua in attendance?

The record is replete with instances of U.S. contempt for, and sabotage of, regional peace efforts. But here is Reagan offering a program that could be mistaken for the one proposed by Oscar Arias, president of Costa Rica.

The one thing they are sure of as they race from parley to parley, at the White House, in the Capitol, is that Speaker Jim Wright (D-Tex.), who actually wrote a draft of the plan, is taking the political risk of his life.

Wright, a student of history, wants to make it, and several months ago before the hearings began, he started making overtures to the new team in the White House, namely chief of staff Howard H. Baker Jr. and national security adviser Frank C. Carlucci about the urgent need for serious diplomacy.

He found them receptive. Wright decided to take a chance that the bad old days, so exhaustively laid out in the Iran-contra hearings, were over. He called in Majority Leader Thomas S. Foley (D-Wash.), Whip Tony Coelho (D-Calif.) and David E. Bonior (D-Mich.), the grave young chairman of the Nicaraguan Task Force. They conferred extensively with Baker and Carlucci, and later with Secretary of State George P. Shultz, who had ringingly endorsed contra aid at the hearings.

The Democrats made the political calculation that Shultz had "won" at the hearings and was finally, firmly, in charge of foreign policy.

Says Coelho, who has one of the most acute political minds in his party, "The speaker thinks these people are on the level. He believes they are willing to take on the right wing to get peace."

The peace offensive coincided with one of the periodic visits of the contra leadership. They did not look like people who were about to have the rug pulled out from under them. Adolfo Calero, the agreeable American puppet, who sent Oliver L. North $90,000 in traveler's checks from his war chest, was beaming.

Obviously, they think the whole thing is another scam.

At a minimum, they expect to get the boon of legitimacy out of it. They seemed of the impression that they would sit down at the table with the Sandinistas and haggle with them as equals over the cease-fire. This is the one thing that Sandinistas have adamantly refused to do. Was this the hidden hook?

The secretary of state said no. The terms could be negotiated bilaterally between the United States and the Sandinistas. The substantive matters, like the size of forces, are less controversial. Nicaragua has agreed to them in previous tentative accords, vetoed by the administration.

Says Coelho, "Maybe they're all back at the State Department winking at each other because they've taken us in again. But the speaker is willing to risk everything on the belief that the White House is willing to negotiate for peace as much as they were willing to fight a war, and we're going with him."