A long, hot campaign is shaping up to fill the seat of retiring Republican Sen. Jim Bunning.

Kentucky Secretary of State Trey Grayson formally kicked off his bid Wednesday in Edgewood, just across the Ohio River from Cincinnati. But the bigger action may be back in Washington. With two dozen U.S. Senators listed as hosts, he hopes to cement his frontrunner status with a $500-a-head fundraiser there next month. Topping the list are Senate Minority Leader Mitch McConnell and Sen. John Cornyn, chairman of the National Republican Senatorial Committee -- a clear sign who the party favorite is, and it's not Rand Paul, son of Texas Rep. Ron Paul, whose wild-card bid could yet spoil the coronation.

Democrats also think Mr. Grayson is the biggest threat, judging by a statement released yesterday comparing the strategies of both GOP candidates. "If Trey Grayson can wrangle enough special interest money to overcome Rand Paul's formidable grassroots fundraising, voters will know who in Washington he is beholden to," said Eric Schultz, spokesman for the Democratic Senatorial Campaign Committee.

An automated poll released last week showed Mr. Grayson leading Mr. Paul by 37% to 26% in the GOP primary race. But the result actually legitimizes the candidacy of Mr. Paul, who raised more than $500,000 in a one-day fundraising "bomb" organized by supporters last week. When matched up against the two favorites for the Democratic nomination, Mr. Grayson still looks stronger: He leads by six or seven points over both Lt. Gov. Daniel Mongiardo and Attorney General Jack Conway. But he still has to get past GOP primary voters. The race may end up testing whether hardcore Kentucky Republicans include the GOP leadership in any indictment of the bailout and spending frenzy in Washington since last fall.

Mr. Grayson's formal entrance into the race coincided with a day of celebration for Kentucky Democrats, who were relishing a special election victory of a formerly Republican state Senate seat. The GOP majority in the upper chamber has been whittled down to 21 to 17, including one independent. All this makes Kentucky a state to watch next year. Not only will a U.S. Senate seat and control of the state senate be up for grabs. A strong push from the governor and pro-gaming forces to allow slot machines at racetracks could also have a potentially interesting impact on turnout.