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ABC News' Jeff Zeleny reports:

Democrats are without a Senate candidate in Kentucky following Ashley Judd's decision to take a pass on challenging Sen. Mitch McConnell, so they are turning to one of the state's favorite past imes to draw attention to the race: the Sweet 16 of the NCAA basketball tournament.

The Democratic Senatorial Campaign Committee is opening its first statewide advertisement today against McConnell, ABC News has learned, by airing a radio spot that sounds like a play-by-play announcer calling a big game.

"It's tournament time and Sen. McConnell's playing for the Washington special interests - against Kentucky," the ad says , with an announcer's voice speaking over the crowd. "Kentucky is trying to move up, trying to provide assistance for workers who lost their jobs and they're blocked by McConnell, who scored big for himself for nearly 30 years."

There may be more realistic opportunities for Democrats to pick up seats next year. But there are fewer targets bigger than McConnell, the Republican Senate leader, as he seeks re-election to a sixth term.

"Kentuckians know that Mitch McConnell is playing for 'Team Washington' and not for Kentucky," said Guy Cecil, executive director of the Democratic Senatorial Committee.

The Democratic campaign will be running as the spirit of basketball is in the air, with McConnell's beloved Louisville Cardinals the top seed in the tournament. Democrats are trying to send a signal that McConnell will not have a free ride to re-election, but Republicans dismiss the suggestion that their Senate leader is in serious peril.

"The hollow DSCC spin that Kentucky will be competitive still hasn't made its way to the Bluegrass State," said Brad Dayspring, a spokesman for the National Republican Senatorial Committee. "The Democrats' top 10 choices to run against Sen. McConnell have now walked away from the race. Perhaps No. 11 is a lucky charm?"

The radio commercial is the latest escalation in the Kentucky race, which has already drawn more advertising than any other race at this early stage of the campaign. McConnell has already raised $7 million in a contest that party strategists believe could cost both sides at least $20 million.

McConnell is also opening a statewide radio offensive in Kentucky, highlighting his speech from the Conservative Political Action Conference earlier this month where he urged conservatives to unite and fight to change the direction of the country.

"If you believe in your heart that the direction Barack Obama wants to take this country is wrong," McConnell says in the ad, "it's time to stand up together and fight back."