Vote Vets, a progressive veterans' group, released a new ad on Thursday morning supporting Sen. Claire McCaskill (D-Mo.) in her reelection campaign. The ad features two Missouri veterans, both of whom served in Iraq, praising McCaskill for her defense of Veterans Affairs medical facilities in the state and her support for the Post-9/11 GI Bill. "She knows it's un-American to turn our backs on those who've served," says one.

The 30-second ad is currently set to run for two weeks in St. Louis and Kansas City. The ad buy, Vote Vets' first of the 2012 election cycle, will cost $200,000. The group said in a press release that "an extension of the buy could be coming."

McCaskill's Republican opponents -- Rep. Todd Akin (R-Mo.), businessman Jon Brunner, state auditor Tom Schweich and former Missouri state treasurer Sarah Steelman -- are locked in a primary battle, although that has not helped the Democrat's chances. A Rasmussen poll released on March 16 showed McCaskill trailing all four Republicans by at least four points. Steelman was the strongest GOP candidate, leading McCaskill by a 51-41 margin.

Watch the full ad below: