The Tea Party-affiliated group is airing two weeks of radio ads attacking the senator in Atlanta, making him their fourth target, alongside Sens. Lindsey GrahamLindsey Olin GrahamCongress punts fight over Dreamers to March Pence tours Rio Grande between US and Mexico GOP looks for Plan B after failure of immigration measures MORE (R-S.C.), Lamar AlexanderAndrew (Lamar) Lamar AlexanderOvernight Health Care: Trump health chief backs CDC research on gun violence | GOP negotiators meet on ObamaCare market fix | Groups sue over cuts to teen pregnancy program GOP negotiators meet on ObamaCare market fix 30 million people will experience eating disorders — the CDC needs to help MORE (R-Tenn.) and Richard BurrRichard Mauze BurrOvernight Finance: Senate rejects Trump immigration plan | U.S. Bancorp to pay 0M in fines for lacking money laundering protections | Cryptocurrency market overcharges users | Prudential fights to loosen oversight Senators introduce bill to help businesses with trade complaints Our intelligence chiefs just want to tell the truth about national security MORE (R-N.C.). Like Burr, Isakson isn't up for reelection until 2016.

"Republicans in Congress can stop ObamaCare by refusing to fund it, but Sen. Johnny IsaksonJohn (Johnny) Hardy IsaksonFrustrated Republicans accuse Paul of forcing pointless shutdown Budget deal is brimming with special tax breaks House funding bill includes bipartisan Medicare reforms MORE refuses to join the fight," the ad intones. "Johnny Isakson voted to give President Obama money to implement ObamaCare earlier this year, and he'll do it again if you don't make your voice heard."

The ad is part of a broader campaign to push Republicans to back Sen. Mike LeeMichael (Mike) Shumway LeeThe 14 GOP senators who voted against Trump’s immigration framework Prison sentencing bill advances over Sessions objections Grassley ‘incensed’ by Sessions criticism of proposed sentencing reform legislation MORE's (R-Utah) campaign to use the impending debate over funding the government to try to force Democrats to defund ObamaCare. So far, 14 GOP senators have signed on, but a number of others have disagreed with the plan.