The Washington-based Democratic Senatorial Campaign Committee transferred "tens of thousands" of dollars to Mongiardo's election fund, campaign manager Kim Geveden confirmed.

Neither Geveden nor a committee spokeswoman would reveal the amount.

It was the first tangible sign that Democratic leaders in Washington have any hope of winning the race. But Mongiardo still faces an uphill battle against a better-funded Republican incumbent, Sen. Jim Bunning.

Cara Morris, spokeswoman for the Senate committee, said the national organization thinks Mongiardo is closing the gap among voters. She cited favorable results from a Mongiardo campaign poll as one of the factors that prompted the donation.

"We are obviously keeping a close watch on the campaign, and we see a lot of movement," she said.

Under election finance laws, national party organizations can transfer up to $466,000 to U.S. Senate candidates in Kentucky.

Morris said the organization had not contributed that amount. She would not say whether Mongiardo can expect more.

Through June, Mongiardo had $600,000 on hand compared with Bunning's nearly $4 million. The Federal Election Commission is expected to release updated numbers later this month.

"If the national liberal Democrats want to throw their money down a hole at a sunken liberal candidate in Kentucky, they can go right ahead," Bunning campaign manager David Young wrote in an e-mail.

It's unclear whether the National Republican Senatorial Committee will make a similar contribution for Bunning.

Republican committee spokesman Dan Allen said the organization constantly re-evaluates races and "reserves the right to make an investment any time."

"Sen. Bunning is well on his way to re-election," Allen added. "But the fact is, we're not going to take any race for granted."

Bunning and Mongiardo will debate for the first time at 2:30 p.m. Monday at WKYT-TV.

The forum will be taped and rebroadcast from 8 to 9 p.m. Wednesday in Lexington and Hazard.