ASSOCIATED PRESS WRITER

ED MCCOLLOUGH

PORT-AU-PRINCE, Haiti (AP)—U.S. warships stopped their first freighter Tuesday in the oil-and-arms blockade of Haiti, while a ‘‘crisis committee’‘ of Haitian lawmakers tried to break a standoff between the army and the rest of the world.

With only 11 days left before the scheduled return of exiled President Jean-Bertrand Aristide, the committee was looking for a way to pass amnesty legislation that Haiti’s military leaders have demanded before they step down.

So far, parliament has been unable to muster a quorum.

In Washington, the Senate rejected a Republican effort to give Congress more say in sending troops to trouble spots such as Haiti.

More battles loomed over amendments proposed by Senate Minority Leader Bob Dole, R-Kan., to require congressional authorization for the use of the military in Haiti and Bosnia.

The proposals reflect a widespread perception in Congress that Clinton has failed to articulate a clear plan for dealing with problems in Bosnia-Herzegovina, Somalia and Haiti.

A U.S. Navy frigate stopped a Belize-flagged ship on Tuesday afternoon. The ship was allowed to proceed after inspectors boarded it and found it was carrying cement, an item not prohibited under the embargo.

‘‘No contraband, no problems, so it was a successful, safe boarding,’‘ said Cmdr. Peter Squicciarini, the commanding officer of the Caron, a destroyer taking part in the blockade.

The six Navy warships taking part in the blockade moved to 3 miles off Haiti’s coast. They stood out clearly on the horizon, their gray superstructure and high decks visible through the Caribbean haze.

‘‘We think visibility is important,’‘ U.S. embassy spokesman Stanley Schrager told reporters.

The ships’ presence is intended to send ‘‘a very clear message to the military authorities … of our determination to see this through,’‘ he said.

Besides the Navy ships, the flotilla includes at least 10 Coast Guard vessels, a French frigate, two Canadian destroyers and a supply ship, and an Argentine navy corvette. The ships are supported by Navy and Coast Guard aircraft.

The effect of the embargo probably won’t be felt for some time; Haiti laid in an estimated three- to six-month stockpile of gasoline before the embargo took effect. But with no further supplies coming in, Haiti’s fragile economy, already the poorest in the hemisphere, could disintegrate.

A U.N.-sponsored agreement for returning Aristide and restoring democratic rule was signed last July by Aristide and army commander Lt. Gen. Raoul Cedras, leader of the September 1991 coup that ousted Aristide. Both did so reluctantly and under international pressure, including sanctions that were lifted after the plan was signed.

The plan broke down last week when Cedras and other officers refused to step down and an unruly crowd turned back a U.S. ship carrying non-combatant troops called for under the U.N. agreement.

Cedras has said he won’t resign until parliament passes legislation granting amnesty to people accused of political crimes since the 1991 coup.

Aristide issued an amnesty decree, but Cedras insists a decree can be revoked too easily.

Parliament hasn’t been able to get a quorum, partly because lawmakers are afraid for their own safety. In addition, Aristide’s opponents in parliament are believed to be using absenteeism as a tactic to block the amnesty legislation and thus the transfer of power.

The crisis committee was considering ways to pass the amnesty legislation, as well as legislation to create a civilian police force free from military control, another sticking point.

The embargo deadline was 11:59 p.m. Monday, and the stage seemed set for a showdown. The flotilla took up its position, and Marines and helicopters moved to the U.S. Navy base at Guantanamo Bay, Cuba, 90 miles northwest of Haiti. Thousands of Haitians fled the capital last weekend.

Stores opened cautiously Tuesday morning. Traffic was light because schools were closed. Government offices stayed closed for a second day, on Aristide’s orders, to mourn the assassination last week of the country’s justice minister.

There were no gas lines, and prices remained about $1.50 a gallon. ‘‘Supplies are normal. There’s no rationing, yet,’‘ a service station attendant said.

Some businesses remained closed out of respect for Aristide, others to assess the potential for violence, and others because their owners have left the capital until at least Oct. 30, the date Aristide is scheduled to return.

‘‘I got here at 6 a.m. and I haven’t had a single customer’‘ in two hours, said a jeweler’s apprentice, standing on a downtown sidewalk next to a small display case. ‘‘I came because I need the money, but there’s no business.’‘

The harsh effects of the embargo on Haiti’s struggling economy may compel both sides to compromise.

Cedras and U.N. envoy Dante Caputo have each said the accord has a chance to succeed. And U.S. Ambassador William Swing showed flexibility Monday night, telling reporters the accord could be interpreted as calling for amnesty legislation.

‘‘Sanctions imposed one more time on this country will not solve the problem,’‘ Cedras said Tuesday on CNN. ‘‘The problem must be solved by dialogue.’‘

Aristide, who won by landslide in December 1990, is Haiti’s first freely elected president.