Updated

Denying that it gave Jean-Bertrand Aristide (search) a rough shove into exile, the United States is insisting the Haitian president resigned and left his embattled country of his own free will.

But black lawmakers and others demanded an investigation into the way the Bush administration treated Aristide in the hours before he left his country and turned up in the Central African Republic. They built their objections around repeated claims by Aristide that U.S. officials forced him out.

With Aristide gone, and rebels who brought him down inside Port-au-Prince (search), Haiti's capital, the first significant U.S. military presence began arriving Monday.

The Pentagon said as many as 400 Marines would be there at the end of the day, with hundreds more to come. As many as 2,000 U.S. troops could eventually go to Haiti to help curb the chaos, but Defense Secretary Donald Rumsfeld (search) said U.S. troops would remain in Haiti only for a short time. An interim international force that could include up to 5,000 troops from France, Canada and elsewhere was expected to stay until replaced by a U.N. peacekeeping force.

Aristide told The Associated Press that his resignation was coerced. He said U.S. agents who came to his home "were telling me that if I don't leave they would start shooting and be killing in a matter of time." It was unclear whether Aristide meant that the rebels or U.S. agents would begin shooting.

"I was forced to leave," Aristide said in a telephone interview from Africa.

Secretary of State Colin Powell and Rumsfeld denied that, but U.S. officials acknowledged privately that Aristide was told that if he remained in Haiti, U.S. forces would not protect him from the rebels who had threatened to kill him.

Powell relayed that news over the weekend in a telephone call to Ronald Dellums, a former California congressman who is now a Washington lobbyist for Aristide. As for Aristide's claims of abduction, Powell said: "He was not kidnapped. We did not force him onto the airplane. He went onto the airplane willingly, and that's the truth."

A small delegation from the Congressional Black Caucus took their misgivings over the end of Aristide's rule in Haiti to U.N. Secretary-General Kofi Annan. One member, Rep. Barbara Lee, D-Calif., said she would raise Aristide's plight Wednesday before the House International Relations Committee.

The lawmakers, as well as Jesse Jackson and international advocacy group TransAfrica Forum, demanded a congressional investigation. They argued that the Bush administration engineered Aristide's ouster by cutting off badly needed aid and supporting his political rivals.

"While President Aristide's own serious errors may have contributed to the problem, the Bush administration's doctrine to follow its lead or be removed seems to be at the core of the current crisis," said TransAfrica director Bill Fletcher Jr.

In a telephone interview Monday night, Aristide said the United States withdrew on Saturday the 19 Americans who had been assigned to his security detail.

A U.S. official speaking on condition of anonymity said Aristide asked the Americans whether some of the 50 Marines that President Bush had sent a week ago to protect the U.S. Embassy in Port-au-Prince might shift to the presidential palace if the rebels drew close.

The answer was no.

Rep. Charles Rangel, D-N.Y., said the pressure put on Aristide to resign seemed to indicate that the Bush administration had sided with "the opposition and the coup people." He worried that further violence could erupt if Haitians believe the United States was behind Aristide's ouster.

Rep. Maxine Waters, D-Calif., said she has problems about ties between Haitian opposition leaders and Roger Noriega, the State Department's top official for Latin America, who played a pivotal role in peace arrangements with other multinational groups before Aristide's departure.

"He is known as a Haiti hater," Waters said Monday. "He's on record, for years, of undermining Haiti, denying them funding."

The United States was among several international donors that froze millions of dollars in aid after Aristide's party swept flawed legislative elections in 2000. U.S. administrations have sent nearly $1 billion in aid to Haiti over the past decade, yet grinding poverty persists; Haiti is the poorest country in the Western Hemisphere.

Opponents say Aristide, the country's only democratically elected president, failed to deliver on his promises to help the poor, used armed gangs to menace his political rivals and allowed corruption fueled by drug trafficking. Aristide denied that.