Rep. Cory Gardner (R-Colo.) accused Sen. Mark Udall (D-Colo.) of lying about ObamaCare.
Gardner is challenging Udall in the midterm election for Udall's Senate seat.
Gardner has used Udall’s vote for the Affordable Care Act, also known as ObamaCare, against Udall in previous ads.
In the latest ad, Gardner points out that more than 300,000 Coloradans received healthcare cancellation notices, but he doesn’t say how many of those people now have insurance through the healthcare exchange.
Udall is one of the more vulnerable incumbents in November’s midterm election. Republicans need to win six Senate seats to gain control of the chamber.