Sen. Jim Bunning (R-Ky.) on Friday vehemently disputed a story in the Louisville Courier-Journal that quoted anonymous sources saying the lawmaker has publicly threatened to resign from the Senate before his term expires next year.

The Courier-Journal newspaper, which posted its story online Friday afternoon, referred to three background sources who claim that Bunning issued the warning Tuesday at a campaign fundraiser in Washington, D.C.

Bunning’s office confirmed the event, but in a statement denied that the Senator informed those who attended that he was considering resigning as a result of his ongoing fight with Senate Republican leaders.

“It’s not true. I intend to fulfill my obligation to the people of Kentucky. If you are going to write something like this, you’d better make your sources known because they are lying,” Bunning said in reference to the Courier-Journal article.

In backing up its story, the Courier-Journal quoted three background sources.

“I would get the last laugh. Don’t forget Kentucky has a Democrat governor,” the first source quotes Bunning as saying.

The suggestion implicit in Bunning’s retirement threat is that the Senate Republican Conference would see its ranks shrink from 41 to 40, leaving it one Senator shy of being able to muster a filibuster.

Kentucky’s governor is a Democrat, and the Bluegrass State allows its chief executive to fill Senate vacancies via appointment. Presumably, Gov. Steve Beshear would appoint a fellow Democrat to fill any vacancy created by a premature Bunning departure.

Bunning has been at odds with Senate GOP leaders for months because the Kentucky Republican has done very little to prepare to run for re-election in a state that has seen Democratic gains of late — including in the House and the governor’s mansion. GOP leaders have voiced their displeasure with Bunning, while hinting that they would prefer that he retire. Many Republicans privately worry that Bunning cannot win re-election in 2010.

However, Bunning has been adamant that he is running for a third term, engaging in a sometimes explosive and extended back-and-forth with National Republican Senatorial Committee Chairman John Cornyn (Texas).