One of the main reasons why Sen. Jim Bunning (R) is widely regarded as the most vulnerable Senate incumbent heading into 2010 is because of his poor fundraising performance. On the day that he reported raising $263,000 in the first quarter, Bunning admitted to local media that his fundraising was going “lousy.—

And while the two-term Senator hadn’t offered any assessment of his second-quarter fundraising as of Friday afternoon, that total certainly wasn’t helped by the postponement of a $500-per-couple event that was scheduled to take place in Lexington today.

Bunning, who serves on the Energy and Natural Resources Committee, was set to appear at a fundraiser hosted by Kentucky Coal Association President Bill Caylor tonight, but late last week, Caylor postponed the event until August because of “late notice— and attendees being on vacation.

Caylor said Friday that he wanted to get people from the oil and gas industry involved in the event, as well as supporters in the coal industry, but because of the late scheduling of the fundraiser, he couldn’t get them on board.

“We were doing this real quickly. Then we realized we had made some snafus,— Caylor said. “We wanted to get other groups more involved. We realized we didn’t have the oil and gas guys.—

Bunning’s office wouldn’t say last week how many fundraising events the Senator has scheduled before the June 30 deadline, but his spokesman said the Senator plans to be in Kentucky for the entire July Fourth recess.

Meanwhile, Secretary of State Trey Grayson (R), who has formed an exploratory committee for the Senate race, has fundraisers scheduled for today in London, Ky., and Tuesday in Lexington.

Supporters at Grayson’s campaign say the secretary of state is on track to report close to $500,000 raised in the second quarter. Grayson only had two months to fundraise this quarter after filing his exploratory committee in early May.