March Madness is taking over the race for the soon-to-be vacant U.S. Senate seat in Kentucky.

The rivalry between Duke University and the University of Kentucky in the annual college basketball tournament is at the center of a political attack ad in the Republican primary, and it's behind a wager made by a candidate in the Democratic primary.

Even Republican Sen. Jim Bunning, who is retiring from the Senate, showed signs of basketball fever a few weeks ago when he complained on the Senate floor about missing a Kentucky game as he held up a vote on the extension of unemployment benefits.

Republican Senate candidate Trey Grayson is attacking his opponent, physician Rand Paul, for asserting that Paul is a fan of the Duke Blue Devils. On his campaign Web site, Grayson offers bumper stickers that say "Beat Duke, Vote Grayson."

In an ad, Grayson, a University of Kentucky graduate, says he would always cheer for "for the Big Blue," a nickname for the Kentucky Wildcats.

And in the Democratic primary, Kentucky Lt. Gov. Daniel Mongiardo offered a wager to the state's attorney general, Jack Conway, that his Wildcats would go farther than Conway's Blue Devils, an offer that Conway declined to accept.

Mongiardo offered to caddy for Conway if Duke went further in the tournament. In return, if Kentucky advanced further, Conway would have to follow Mongiardo on a hunting trip.

"As a longtime college basketball fan, it's unfortunate that Daniel Mongiardo's campaign has decided to cheapen America's greatest sporting event by injecting lowbrow political attacks into the NCAA tournament," Conway spokeswoman Allison Haley said in a statement to Fox41 in Kentucky.

Mongiardo spokeswoman Kim Geveden replied: "I guess that fact that Jack is trailing Daniel by 18 points in the latest Bluegrass Poll has removed any sense of humor Jack may have had. But he really should lighten up and take Coach Cal's advice – 'have fun.'"