The ads indicate that Republicans believe Obama's healthcare law remains a winning issue for the party. "ObamaCare," as its called by Republicans, has played a central role in much of Republicans' messaging this cycle.

Most of the ads focus on what they characterize as the law's adverse affect on the economy, with some highlighting cuts to Medicare or increased taxes. The ads running against Democrats in Nevada, however, veer away from the healthcare attack: against Horsford, the NRCC highlights Horsford's business and fundraising past, and frames Oceguera as wasting taxpayer dollars.

The ad running against Nolan in Minnesota is the third ad out from Republicans this week attacking the former congressman. Republican super-PAC Congressional Leadership Fund also launched two other ads in Minnesota, targeting Nolan's support for the healthcare law and Environmental Protection Agency regulations. A recent poll commissioned by a number of Democratic groups showed Nolan leading freshman Rep. Chip Cravaack (R-Minn.) by 3 percentage points.

—This post was published at 11:19 a.m. and updated at 11:48 p.m.