Mr. Martin, in a series of interviews, did not dispute his influence in Obama rumors.

“Everybody uses my research as a takeoff point,” Mr. Martin said, adding, however, that some take his writings “and exaggerate them to suit their own fantasies.”

As for his background, he said: “I’m a colorful person. There’s always somebody who has a legitimate cause in their mind to be angry with me.”

When questions were raised last week about Mr. Martin’s appearance and claims on “Hannity’s America” on Fox News, the program’s producer said Mr. Martin was clearly expressing his opinion and not necessarily fact.

It was not Mr. Martin's first turn on national television. The CBS News program "48 Hours" in 1993 devoted an hourlong program, "See You in Court; Civil War, Anthony Martin Clogs Legal System with Frivolous Lawsuits," to what it called his prolific filings. (Mr. Martin has also been known as Anthony Martin-Trigona.) He has filed so many lawsuits that a judge barred him from doing so in any federal court without preliminary approval.

He prepared to run as a Democrat for Congress in Connecticut, where paperwork for one of his campaign committees listed as one purpose “to exterminate Jew power.” He ran as a Republican for the Florida State Senate and the United States Senate in Illinois. When running for president in 1999, he aired a television advertisement in New Hampshire that accused George W. Bush of using cocaine.

In the 1990s, Mr. Martin was jailed in a case in Florida involving a physical altercation.

His newfound prominence, and the persistence of his line of political attack  updated regularly on his Web site and through press releases  amazes those from his past.

“Well, that’s just a bookend for me,” said Tom Slade, a former chairman of the Florida Republican Party, whom Mr. Martin sued for refusing to support him. Mr. Slade said Mr. Martin was driven like “a run-over dog, but he’s fearless.”