Larry Klayman, the inexhaustible litigious gadfly who has hounded government officials from the Clintons to Vice President Cheney in the name of fighting corruption, said he will run for the Senate seat now held by Sen. Bob Graham (D-Fla.).

Klayman, a former international trade lawyer who founded the conservative nonprofit group Judicial Watch and made it into a legal and fundraising power, will today officially declare his candidacy for the Republican nomination in Tampa, Fla., he said in a brief telephone interview Monday.

Klayman is a resident of Miami and has commuted to Washington, D.C., since he founded Judicial Watch and served as its chairman and general counsel in 1994.

Graham, who is pursuing the Democratic presidential nomination, has not yet indicated whether he will seek to hold onto his Senate seat. Others seeking the GOP nod for the election include former Rep. Bill McCollum and Rep. Dave Weldon.

Klayman’s campaign Web site, KlaymanSenate.com, promised to continue attacks on a particularly favorite target in dozens of Judicial Watch lawsuits since 1994: Sen. Hillary Rodham Clinton (D-N.Y.).

“In the United States Senate, Larry will continue to be the ‘antidote’ to Hillary Clinton’s corrupt practices and self-serving, liberal agenda,” the Web site said.

Klayman and his group became an almost regular feature in the courtroom of U.S. District Judge Royce Lamberth during the final term of then-President Bill Clinton. Klayman rarely missed any opportunity to file legal challenges and scores of press releases denouncing the Clintons, former Vice President Al Gore and former Attorney General Janet Reno.

But with the ascension of President Bush and Republican rule in both houses of Congress, Klayman shocked many of his conservative allies by turning his legal aim at Republicans, including House Majority Leader Tom DeLay (Texas) over aggressive fundraising tactics and Cheney for his ties to the Halliburton Co. and the secrecy of a high-level energy task force.

Indeed, Klayman’s most successful legal triumph appears to be the victory handed to him by the U.S. Circuit Court for the District of Columbia, which recently upheld a lower-court decision ordering Cheney to disclose certain documents about the closed-door activities of the energy task force chaired by Cheney. The administration said this month that it will appeal that ruling to the Supreme Court.

Klayman’s campaign Web site, though, doesn’t mention the Cheney litigation, instead focusing on Judicial Watch’s record against the Clintons and other matters closer to Florida.

For example, Klayman highlighted a 2001 lawsuit he filed in Belgium to formally charge Cuba’s Fidel Castro with torture and violation of human rights under the Belgian War Crimes laws established in 1999. He also touted his role in legal challenges to the Clinton administration’s decision to return 6-year-old Elian Gonzales to Cuba during a bitter and emotional confrontation with the vocal anti-Castro community in Miami.

Klayman also said he would sponsor legislation that would require visa expiration dates to be printed on the driver’s licenses and school records of all foreign visitors to crack down on those in this country illegally.

Klayman would also sponsor a law to bar entry into the United States by any person whose country of origin is on the State Department’s Terrorist Watch List, and he would seek to have Saudi Arabia added to that list.

Klayman demonstrated his fundraising prowess with Judicial Watch. In 2001, the group reported raising more than $17.5 million, much of it through direct mail. That number was even higher during the Clinton administration, according to Internal Revenue Service records.

As news of Klayman’s electoral bid spread Monday, some of his legal sparring partners expressed surprise at the new course.

“It’s an amazing turn of events for somebody who seems so anti-politics,” said Stan Brand, a defense lawyer who represented former White House aide George Stephanopoulos during a notorious deposition conducted by Klayman. “Guess stranger things have happened.”