The campaign for the GOP nomination to take on two-term Florida Sen. Bill Nelson (D) just took a nasty turn.

The frontrunner for the Republican nod, Rep. Connie Mack IV, has faced a slew of bad press in recent days, including reports about a barroom brawl and unpaid bills. That led former Sen. George LeMieux, his main rival for the nomination, to hold a news conference this morning slamming Mack.

LeMieux also released a statement this afternoon, calling Mack “the Charlie Sheen of Florida politics” and saying he was unfit to serve as the Sunshine State’s junior Senator.

Minutes earlier, Mack campaign manager Jeff Cohen released a sharply worded open letter to LeMieux emphasizing the former Senator’s link to former Gov. Charlie Crist (I), who is politically toxic among Republican primary voters and for whom LeMieux worked.

“George, this isn’t just about politics. No longer can you be the liberal (or is it amoral?) political operative who created Charlie Crist. Now it’s about the future of our country,” Cohen wrote.

“The fact that you would hold a press conference that does nothing more than help Bill Nelson and gives you a few more lines in the newspaper by trying again to take no prisoners is frankly why you’re not suitable, eligible or desirable to serve in any elective office, and certainly not in the United States Senate,” Cohen added. “[Y]our behavior is damaging to you, our Party, our state and the country.”

The back-and-forth, with both candidates’ campaigns calling their opponent unfit to serve, is as clear a sign as any that the gloves are off in Florida and that it will be a long road to the Aug. 14 primary.

Roll Call rates the Florida Senate race as Leans Democratic.