WASHINGTON — Mayor Giuliani, a Republican presidential candidate, joked yesterday about reports that New York’s five Mafia families discussed, but decided against, killing him in 1986 when he was a mob-busting federal prosecutor.

“That was one vote I won, I guess,” Mr. Giuliani said yesterday on Mike Gallagher’s syndicated radio show. Mr. Giuliani said there have been other contracts for his life, including an $800,000 hit when he was first U.S. attorney.

“After 5 1/2 years of being U.S. attorney, they put out another contract to kill me, another group, for only $400,000,” Mr. Giuliani said.

Mr. Giuliani told reporters later in Washington he didn’t worry much about contracts on his life. “I don’t know, go ask the mob, how do I know if the mob really tried to whack me?” Mr. Giuliani said, laughing. He added that he knew of two or three plots to kill him but didn’t remember the one that emerged this week.

“So there was more than one, but the FBI did a really good job of getting them resolved,” he said. “I always felt it was my obligation to kind of put that out of my mind and just do my job.”

Before Mr. Giuliani became New York mayor, he had a track record of high-profile mob prosecutions. In 1986, Mr. Giuliani indicted the heads of the five families. The mobsters purportedly discussed the hit that year.

The details about the plot — which never took shape — were given to an ex-FBI agent, Roy Lindley DeVecchio, by the late Gregory Scarpa Sr., a capo-turned-informant, according to the testimony of an FBI agent, William Bolinder, during a murder trial in New York.

In testimony Wednesday, Mr. Bolinder said that Mr. DeVecchio’s 1987 debriefing report stated Scarpa told him the late Gambino crime boss John Gotti was for ordering the hit, and had the support of the leader of the Colombo crime family.

However, Mr. Bolinder said, the heads of the Bonanno, Lucchese, and Genovese groups were against the idea, and it never materialized.