The Republican National Committee is launching ads in a dozen states this week, mostly incumbents who supported President Barack Obama's health care law.
The radio ads, which will run Tuesday and Wednesday, will attempt to tie Democrats across the country to Obama's failed promise that Americans could keep their existing insurance plans.
"Obamacare is going to be the issue in 2014," RNC chairman Reince Priebus told reporters.
The ads target Sens. Mark Begich, D-Ak. Mark Pryor, D-Ark., Mark Udall, D-Colo., Mary Landrieu, D-La., Kay Hagan, D-N.C., Jeanne Shaheen, D-N.H., Jeff Merkley, D-Ore., Mark Warner, D-Va., and Reps. Bruce Braley, D-Iowa, Gary Peters, D-Mich., Tim Bishop, D-N.Y. and Nick Rahall, D-W.Va.
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The ads will also run in Spanish in Colorado and Virginia, in Vietnamese in Louisiana and in Korean in Virginia.
The RNC did not disclose the cost, but some estimates put the buy at only at a couple thousand dollars.
Democrats will be defending 21 seats. Republicans need a net gain of six seats to wrest control of the Senate from the Democrats.
"Let’s be clear, expanding access to health care, unemployment benefits, minimum wage and education – these are all programs that will help grow the middle class and the Republicans have voted time and again to gut them," Democratic National Committee spokesman Michael Czin said.