A conservative super-PAC is slamming Rep. Jack KingstonJohon (Jack) Heddens KingstonDan Rather: The voice of Florida survivors will change status quo Shooting survivors push for action in Trump meeting Rubio: 'Disgusting group of idiots' made up claim that shooting survivors are actors MORE (R-Ga.) as a "career politician" and the "King of earmarks" in a new ad, the latest salvo in Georgia's crowded Senate race.

Citizens for a Working America, a South Carolina-based super-PAC, blasts Kingston for his work on the Appropriations Committee in the ad. The group is spending a half-million dollars to run the spot on Atlanta television.

"Career politician Jack Kingston's been in Washington over 20 years. So what's he done? Kingston earned the title 'King of Earmarks.' He voted to spend billions of taxpayer dollars on Obama's Cash for Clunkers used car program, and voted to raise the debt ceiling. Kingston even took thousands in pay raises. Now Kingston wants a promotion to the Senate. A promotion? Well, conservatives have message: Hey Jack, you're not going back."

Kingston is establishment Republicans' favored candidate in the five-person primary. He's been able to leverage a big fundraising edge into early TV ads that have put him near the top in most polling, but this is the first sustained attack on his record in the race.

The super-PAC attacking him has had an unusual history. Originally formed to attack then-Rep. John Spratt (D-S.C.) in 2010, it went on to back Rep. Michele Bachmann (R-Minn.) before abruptly shifting to former Massachusetts Gov. Mitt Romney (R) in the 2012 GOP presidential primaries.

Kingston is competing for one of two primary runoff slots against businessman David Perdue, former Georgia Secretary of State Karen Handel and Georgia Reps. Phil Gingrey and Paul Broun. With less than a month until the primary, polling shows a tight race.

Democrats are hopeful a long and nasty primary could help them win the seat, and are excited about their candidate, former charity executive Michelle Nunn (D).