A terrorism trial set to get under way in Florida next month could have repercussions for Washington politicians at both ends of the political spectrum.

Lawyers for a former computer science professor charged with being the head of the American branch of Palestinian Islamic Jihad, Sami Al-Arian, have named more than 20 political figures with whom he claims to have had conversations in the years leading up to his indictment in 2003.

The figures cited in the case include Presidents Bush and Clinton, Senator Clinton, and a top adviser to Mr. Bush, Karl Rove.

In a letter filed in federal court in Tampa last week, a lawyer for Mr. Al-Arian, William Moffitt, said he believes surveillance tapes may exist of his client speaking with Republicans such as House Speaker Dennis Hastert, former House Speaker Newt Gingrich, Rep. Henry Hyde of Illinois, and Senator Lott of Mississippi. Mr. Al-Arian may also have had recorded contacts with Democrats, including Rep. Barney Frank of Massachusetts, Rep. James Moran of Virginia, Rep. Cynthia McKinney of Georgia, and the former House minority whip, David Bonior, according to the letter, which asked prosecutors to turn over all such recordings to the defense.

Mr. Moffitt said in a brief interview yesterday that he now has obtained tapes or transcripts of some of those conversations. “Some of them are no longer missing,” the defense attorney said.

Mr. Moffitt said if he seeks to use those recordings, he might call some of the politicians on the list to testify to the tapes’ accuracy. However, he declined yesterday to be more specific about whom he might subpoena. Mr. Moffitt said he was reluctant to telegraph his strategy to prosecutors.

“There’s no way I should be forced to exchange a witness list,” Mr. Moffitt said. “I’m not in a position to say whether some of those people will be called or not.”

Mr. Al-Arian and three other men are scheduled to go on trial May 16 on charges they operated as an American front for Palestinian Islamic Jihad, a terrorist group that has waged a campaign of bombings and other violent attacks against military and civilian targets in Israel. Mr. Al-Arian, 47, faces charges of racketeering conspiracy, extortion, money laundering, and providing material support to a terrorist organization.

A Washington-based terrorism expert who has tracked Mr. Al-Arian’s activities for more than a decade, Steven Emerson, said the defense’s gambit to expose Mr. Al-Arian’s political Rolodex could leave many politicians red-faced. “It will certainly be embarrassing to the leaders who met with Al-Arian, and it will be embarrassing to the political consultants who met with Al-Arian,” Mr. Emerson said.

The letter listing Mr. Al-Arian’s alleged political contacts is dated September 2004, but was filed recently as part of a government bid to block his lawyers from arguing at trial that his actions were part of a legitimate political campaign on behalf of Palestinians.

The public filing of the politicians’ names was first reported by the Tampa Tribune.

After recounting Mr. Al-Arian’s meetings with Mr. Bush, Mr. Clinton, and others, Mr. Moffitt wrote, “Dr. Al-Arian’s access to these political figures coupled with the fact that there was public source information regarding many of the contentions that form the basis of the government’s indictment seem to belie the notion that Dr. Al-Arian was in any way considered by anyone in the intelligence or law enforcement communities to be any kind of threat to the United States or a threat to harm any officials of the United States.”

Among others named in the letter as contacts of Mr. Al-Arian were: a former chief of counterterrorism at the CIA, Vincent Cannistraro; a Republican political consultant, Grover Norquist; a former Republican congressman from Georgia, Bob Barr; a former Republican congressman and homeland security official, Asa Hutchinson; Rep. Jim Moran of Virginia, a Democrat; Rep. Nick Rahall of West Virginia, a Democrat; Rep. Tom Davis of Virginia, a Republican, and a former Republican senator from Michigan who recently stepped down as energy secretary, Spencer Abraham.

Most of those named either declined to comment or could not be reached.

Mr. Cannistraro confirmed that he has been subpoenaed to testify as a witness for the prosecution in the case, but he declined further comment.

Mr. Frank said in an interview he was confident he had never spoken with Mr. Al-Arian. “I certainly never talked to him. I’d remember that,” the congressman said. “I’ve never heard of this guy before, to my knowledge.”

Mr. Frank said his staff had searched his files for any correspondence from Mr. Al-Arian and found nothing.

In the late 1990s and the early years of this decade, Mr. Al-Arian, a Kuwaiti-born naturalized American, was politically active on behalf of Palestinian Arab and Arab-American causes. He was also secretly under regular court-ordered surveillance as a suspected terrorist. During that time, Mr. Al-Arian led a campaign against the use of classified evidence in deportation proceedings, such as one involving his brother, Mazen Al-Najjar.

That campaign, which drew support from civil libertarians on the left and the right, coincided with a determined attempt by Republicans to court Arab-American voters. The overlap of these two efforts helped Mr. Al-Arian win audiences with prominent political figures.

In the waning days of the 2000 presidential race, Mr. Bush unexpectedly embraced legislation that would have prohibited the government from using so-called secret evidence in deportation cases, unless officials were willing to share at least a summary of that evidence with the person facing expulsion from America.

“Bush rode in to appeal to Muslims,” Mr. Emerson said. “There’s no doubt that the Republican advisers who had met with the Islamic groups decided it was something they were going to endorse.”

In March 2000, then-candidate George W. Bush and his wife, Laura, were photographed with Mr. Al-Arian and his family at a strawberry festival in Florida. The White House later said such photos are commonplace.

In June 2001, the Secret Service removed Mr. Al-Arian’s son, Abdullah, from a meeting at the White House complex between Muslim leaders and one of Mr. Bush’s top aides, Mr. Rove. Mr. Bush later wrote to Mr. Al-Arian’s wife, Nahla, apologizing for her son’s ejection.

In September 2001, after the terrorist attacks against America, Mr. Al-Arian had a highly publicized, heated interview with a Fox News television host, Bill O’Reilly. Soon thereafter, Mr. Al-Arian began receiving threats and was put on paid leave by the University of South Florida. The school, which had faced years of pressure to take action against the professor, fired him after he was indicted in February 2003.

A former terrorism prosecutor, Andrew McCarthy, called the elder Mr. Al-Arian’s entree at the White House and on Capitol Hill “extremely curious.” However, he said that as a legal matter, Mr. Al-Arian’s political contact should be excluded from the trial as irrelevant.

“It wouldn’t matter what President Bush or President Clinton thought,” Mr. McCarthy said.

A defense motion to change the trial venue, currently set for Tampa, is expected to be filed later this week.