Rep. Ken Lucas (search), the only Democrat in Kentucky's congressional delegation, announced Monday he would not run for a fourth term next year.

He endorsed television personality Nick Clooney (search), father of actor George Clooney and brother of the late singer Rosemary Clooney, as his successor in northern Kentucky's 4th District. It will be Clooney's first run for elective office.

Lucas said he would honor a pledge he made in his first campaign to limit himself to three terms. It was a reversal from earlier this year, when he said he would run for a fourth term after all. That decision had become "an ever-increasing problem for me and my conscience," Lucas said Monday.

"I have always considered myself a citizen legislator," Lucas said in a statement. "In my three previous elective positions, I have voluntarily stepped down each time."

Lucas, 70, known as a conservative Democrat who frequently votes Republican, said his decision came after numerous conversations with Clooney.

"I determined that if there was a quality Democratic candidate, I would step aside," Lucas said. "If there was not, I would stay in the race."

Clooney, 69, announced his candidacy for the 4th District seat in a news release Monday.

He said he will stake out positions on issues after talking to voters. "I will tell you what I believe to be the truth, whether you agree with me or not, whether it is politically correct or not, whether an election hinges on it or not," Clooney said in a statement.

Clooney is the former host of cable's "American Movie Classics (search)," and worked for years as a reporter and anchorman in Cincinnati.

Republican Geoff Davis, whom Lucas narrowly defeated in 2002, is already campaigning for the seat. "We look forward to a spirited campaign," said a spokesman for Davis, Justin Brasell.

Lucas said he decided to retire before his party lost the governor's election on Nov. 4, ending a 32-year Democratic reign.