Crossroads GPS is hitting the airwaves Wednesday with issue ads against Democratic candidates in five Senate battleground states.

The Republican-aligned nonprofit, which is affiliated with the American Crossroads super PAC, is dropping $1.2 million on the TV ad buy, which was first reported by the Hotline. The ads will air in Missouri, Montana, Nevada, North Dakota and Virginia through May 5.

American Crossroads and Crossroads GPS are major players in the 2012 elections and could spend one-third of a potential $300 million combined budget on House and Senate races this cycle. This round of ads is focused on two Democratic Senators, two open Democratic seats and protecting one Republican Senator.

Republicans, who need to pick up four seats to win the Senate majority, are hoping to defeat Sen. Claire McCaskill (Mo.), Sen. Jon Tester (Mont.), former Virginia Gov. Tim Kaine and former North Dakota Attorney General Heidi Heitkamp. Sen. Dean Heller (R-Nev.) holds one of the GOP’s most vulnerable seats and is facing Rep. Shelley Berkley (D).

Roll Call rates all but one of the races as a tossup. North Dakota currently rates Leans Republican.