The advocacy group Senate Conservatives Action announced Tuesday that it will spend six figures on a new television ad bashing Senate Minority Leader Mitch McConnell -- but national Republicans are brushing off the buy.

Senate Conservatives Action, the PAC of the Senate Conservatives Fund that last week endorsed McConnell's Republican primary opponent, Matt Bevin, will spend $330,000 to air the television ad across Kentucky, the group said. The 30-second spot attacks McConnell for his role in negotiations to end a 16-day government shutdown by restoring government funding, but without blocking the implementation of Obamacare.

"Conservatives asked Mitch McConnell to lead the fight against Obamacare," the ad's narrator says. "He didn't listen."

But Brad Dayspring, a spokesman for the National Republican Senatorial Committee, dismissed the group's latest attack on McConnell as "just a dumb ad."

"It's an 80/20 issue in Kentucky, and the ad is on the 20 side," Dayspring tweeted, referring to recent polls showing that only 20 percent of voters supported shutting down the government to block Obamacare.

The new conservative group's ad is only the latest in its anti-McConnell campaign plan. The group also spent $340,000 last month on an ad attacking McConnell for not defunding Obamacare as part of a larger government funding measure.