While Democrats up for re-election are facing heat over Obamacare, a Democratic-aligned super PAC launched a TV ad targeting the leading Republican in the North Carolina Senate race on the issue of health care.

According to a Republican tracking ad buys, Senate Majority PAC is spending $736,000 over the next two weeks across four media markets to defend Democratic Sen. Kay Hagan and criticize her top Republican challenger, state Speaker Thom Tillis.

It’s the second time in a month that the super PAC has come to the aid of Hagan. The ad can be found on a website run by Senate Majority PAC. It touts Hagan’s work to protect Medicare and Social Security, while also slamming Tillis for siding “with insurance companies.”

A spokesman for the super PAC confirmed the ad buy but said it was probably closer to $750,000. The ad is part of the group’s efforts to defend Democratic incumbents and candidates against GOP-aligned outside groups.

The race is rated Tossup/Tilts Democratic by Rothenberg Political Report/Roll Call.