In Tuesday's primary, Secretary of State Trey Grayson is considered the mainstream GOP candidate while eye surgeon Rand Paul, son of U.S. Rep. and 2008 presidential candidate Ron Paul, has been backed by Tea Party movement activists. They're leading the field of six GOP candidates running to try to keep the retiring senator's seat in the Republican fold.
Rand Paul started out as a long shot for the Republican nomination but has surged ahead of Grayson, enjoying a double-digit lead hovering around 16 percentage points, the Bluegrass Poll conducted for The (Louisville) Courier-Journal last week indicated.
Paul says Kentucky's Republican contest also is a test of the Tea Party, a loose confederation of grassroots organizations that favor smaller government, among other things, Fox News reported.
"This will be a big test. It's gonna be a statewide test of the muscle and the clout of the Tea Party," commented Paul, who said he was in the Tea Party before there was a Tea Party. "Everywhere I go, I'm amazed by it. It's big and it's gonna propel us to victory."
Paul campaign manager David Adams told The Courier-Journal the steady climb in Paul's polling numbers "reflects the trend in Kentuckians' enthusiasm for Rand's message."
Grayson's campaign isn't buying it.
"If Rand Paul is ahead, then why is he running such a negative campaign?" asked Nate Hodson, Grayson's campaign manager. "In our own polling we find the race to be very close, with lots of undecided voters."
Grayson racked up an impressive list of endorsements, including former Vice President Dick Cheney, Kentucky Rep. Hal Rogers and Senate Minority Leader Mitch McConnell -- who happens to be from the Bluegrass State and hand-picked Grayson for the race.
"Kentuckians need a senator who will work with me and the rest of our federal delegation to fight for our values and priorities," Rogers said. "Trey Grayson is the candidate who will do just that. We need him in the U.S. Senate to stop the liberal Democrats from bankrupting our country."
Paul's backers aren't slackers, either. Endorsing him are former Alaskan Gov. Sarah Palin, Sen. Jim DeMint of South Carolina and Bunning.
Armchair political handicappers say Grayson's ties with McConnell may be a hindrance. Paul said he thinks McConnell's longevity in Washington doesn't help Grayson's cause, The Washington Post reported.
"They go, and they stay too long, they lose their way, and as they do they become corrupted by the system," Paul said. "The longer you're there, the more you succumb to the power, the more you think you are somehow different or more important than the rest."
Grayson rejected the notion the race is more of a referendum on McConnell.
"He's (Paul) actually got more D.C. ties than me," Grayson said.
Also on the Republican ticket are Gurley Martin, Bill Johnson, Jon Scribner and John Stephenson.
On the Democratic side, Lt. Gov. Dr. Dan Mongiardo has been hanging onto a slight lead, but observers say momentum may be shifting to state Attorney General Jack Conway. The Bluegrass Poll last week indicated Mongiardo was ahead a scant 1 percentage point.
Conway's campaign has been hoarding cash for nearly a year and has been putting it to use for the last two months, launching a barrage of television ads in the Louisville and Lexington markets along the Interstate-64 corridor.
Democrats also on the primary ballot include James Buckmaster, Darlene Fitzgerald Price and Maurice Sweeney.
CQ Politics rates the eventual Senate race in November as a toss-up.
Real Clear Politics rates the November race as "Likely Republican" because, even though races have tightened, the outlook doesn't favor Democrats. Only 41 percent of Kentuckians approve of U.S. President Barack Obama's job performance, compared to 59 percent expressing disapproval. Sixty percent favor an effort to repeal healthcare legislation.