Flamboyant Iraqi politician Ahmed Chalabi denied yesterday that he had misled the United States on Saddam Hussein's weapons-of-mass-destruction programs and offered to testify before Congress about allegations that he had duped the Bush administration into going to war by providing bad intelligence.

"This is an urban myth," he said in a speech at the American Enterprise Institute. Chalabi dodged questions about what happened to Iraq's nuclear, chemical and biological programs as "not useful" to discuss today. "It's more important to look to the future than to the past," he said.

Chalabi's high-profile visit coincided with the low-key visit to Washington of the man many in Baghdad and Washington suggest is more likely -- at least at this stage -- to be Iraq's next prime minister after the Dec. 15 elections for a permanent government. Adel Abdul Mahdi, Iraq's vice president and former finance minister, is meeting many of the same senior U.S. officials, but the two visits reflected both controversies and prospects in Iraq.

While Chalabi was forced to deal with his past roles in highly publicized ways, Mahdi was able to more quietly focus on issues at the heart of Iraq's future, such as the prospect of permanent U.S. military bases and the need for Shiites and Sunnis to form their own regions -- or perhaps one region together -- in Iraq. Mahdi met almost three times as long with Secretary of State Condoleezza Rice as did Chalabi, U.S. officials noted.

The two Iraqis are now widely considered to be the top candidates to lead Iraq's next government. Both are Shiite politicians who ran in January in the same United Iraq Alliance, a coalition of predominantly Shiite parties. But Chalabi recently broke away to form his own nonsectarian coalition.

Chalabi's meeting yesterday with Rice was the first stop in a weeklong tour that ends more than two years of virtual exile from Washington. He is also scheduled to meet Vice President Cheney, Defense Secretary Donald H. Rumsfeld, Treasury Secretary John W. Snow and national security adviser Stephen J. Hadley.

Chalabi remains a lightning rod for the Iraq war. An FBI probe into allegations that Chalabi provided highly sensitive U.S. intelligence to Iran -- involving U.S. intelligence breaking a secret Iranian code for transmitting encrypted messages -- is still "open and active," FBI spokesman Bill Carter said. Several current and former government officials have been interviewed as part of the investigation, he added.

At the AEI, Chalabi denied he had ever passed intelligence to Iran. During his stop in Tehran en route to Washington, he said he had raised concerns that Iran is using its influence with Iraq's Islamic parties. "This is a project Iran is ill advised to pursue," he said.

In one of several expressions of concern about Chalabi's visit on Capitol Hill, three Democratic members of the Senate Judiciary Committee yesterday wrote Attorney General Alberto R. Gonzales to press for Chalabi to sit down with FBI investigators rather than meet Cabinet members. Democratic Sens. Edward M. Kennedy (Mass.), Richard J. Durbin (Ill.) and Patrick J. Leahy (Vt.) asked Gonzales if the FBI would be interviewing Chalabi about the Iran allegations, and whether the attorney general had advised the White House about the appropriateness of meeting with Chalabi.

In a letter to Chalabi, 18 House members asked the MIT-educated former banker to meet with them to explain his past actions and "help the people of both Iraq and the United States to understand why we are at war today." The letter cited hundreds of pages of supposedly firsthand information that Iraq had mobile biological and chemical weapons facilities -- information provided by a man dubbed an "Iraqi chemical engineer," code-named Curveball, who turned out to be the brother of a Chalabi lieutenant. The information, used by then-Secretary of State Colin L. Powell at the United Nations, was "entirely fabricated," the letter said.

The White House was defensive in justifying the talks with Chalabi, who was convicted in absentia in Jordan more than a decade ago of embezzlement and fraud and sentenced to 22 years in prison. White House press secretary Scott McClellen noted that Chalabi is "an elected leader of the Iraqi government" in charge of key issues such as oil, budget and infrastructure.

"The Iraqi people are deciding their future and they have a representative government that was elected by the Iraqi people," he said. "We are supportive of helping the Iraqi people move forward and build a democratic future."

In contrast, Mahdi drew little publicity in his own talks. In an interview with Washington Post editors and reporters, the economist said a premature withdrawal of U.S. troops would leave a "very dangerous" vacuum. In talks with Rumsfeld, Mahdi said he had made clear he is "not averse" to a permanent base for U.S. troops in Iraq.

Mahdi's older brother, a Cabinet adviser, was killed Oct. 30 in a drive-by shooting. But he said he and Rumsfeld agreed on the need to see fewer U.S. troops in Iraq's urban areas as soon as possible.

Mahdi also said Iraq's Arab population, both Shiite and Sunni, needs to organize in one or more regions to help politically and economically balance the new northern Kurdistan region. Stressing the need to bring the Sunni minority into the new Iraq, he said one possibility is to have the 15 non-Kurdish provinces form one region with Samarra as its capital. He said the Shiite majority is not interested in imposing any formula on the Sunnis that might deepen fears or alienation. "We're realistic," he said.

Iraqi politician Ahmed Chalabi told U.S. leaders that "it's more important to look to the future than to the past."

Adel Abdul Mahdi drew little publicity in his U.S. talks.