Sen. Jim Bunning of Kentucky said Monday he will not run for a third term in 2010, citing a lack of campaign money and interference from Senate Republicans who were pushing for him to exit the race.
In a statement issued by his office, Bunning said his GOP colleagues had done "everything in their power to dry up my fundraising."
Bunning, 77, has been considered the GOP's most vulnerable senator since a razor-thin re-election in 2004 and a public spat with Senate Minority Leader Mitch McConnell of Kentucky, who has made it clear he would like his embattled colleague to retire as he tries to boost his party's numbers in the Senate.
The latest election filings show that from April through June, Bunning raised less than half the total of Kentucky Secretary of State Trey Grayson, a 37-year-old potential primary candidate.
In the statement, Bunning, first elected to Congress in 1986, said that to win a general election, a candidate has to be able to raise millions of dollars for advertising and campaign events.
"The simple fact is that I have not raised the funds necessary to run an effective campaign for the U.S. Senate," Bunning said.
Grayson and Rand Paul of Bowling Green, Ky., son of Rep. Ron Paul of Texas, a former presidential candidate, have been eyeing the race.
Grayson began the campaign saying he would not challenge Bunning but has since modified his position to say only that he has no plans to do so. Paul has said he'd announce before Aug. 20 on whether he'd get in.
Grayson has raised more than $600,000 for his exploratory committee. Bunning has $595,000 on hand but has been raising money since 2005.
Bunning, who was a baseball pitcher with a Hall of Fame career before he entered politics, declined to endorse a candidate in the Republican primary, but he said he's certain the seat will stay in GOP hands.
"The Republican Party needs more people with strong principles and convictions that can stand up to the temptations of political power that have engulfed so many of our leaders after they arrive inside the beltway," Bunning said.
McConnell did not refer to their differences in a statement following Bunning's announcement, saying he has been honored to work with his colleague.
"Kentucky is a far better place because of his service," McConnell said.