The GOP-aligned super PAC American Crossroads launched a major ad campaign in  North Carolina on Tuesday with a commercial supporting state House Speaker Thom Tillis (R) as he runs in a contested Republican primary for U.S. Senate.

The new ad, which contrasts Tillis with Sen. Kay Hagan (D-N.C.), is the first commercial in a a four-week, $1.1 million Crossroads buy leading up to the May 6 primary. A candidate must win more than 40 percent to secure the nomination without a runoff, which Crossroads appears to want Tillis to avoid.

The ad tethers Hagan to Obama on health care and the state's voter ID law before pivoting to a defense of the Republican's record on the same issues.

"Thom Tillis. True to our values," says the narrator.

The Washington Post first reported the ad was for Tillis Tuesday morning.

The ad marks the second time in recent weeks Crossroads has hit the airwaves on behalf of a Republican running in a contested  Senate primary. In Alaska, the group unveiled an ad supporting former state attorney general Dan Sullivan (R), The Washington Post reported last week. The commercial featured former secretary of state Condoleezza Rice vouching for Sullivan.

Tillis is the frontrunner for the GOP nomination, the scant public polling on the GOP race reveals. He faces lesser-known contenders running to his right, such a physician Greg Brannon (R) and Baptist minister Mark Harris (R).

North Carolina has emerged as a central focus of both parties in the battle for the Senate, and GOP groups have blitzed the airwaves. Americans for Prosperity, a group backed by the billionaire Koch brothers, has already spent more than $7.2 million in the race. Through the middle of last week, Republican ad spending had outpaced Democratic money by about $6 million.

"It's pretty unbelievable for Karl Rove to spend over a million dollars to praise Thom Tillis' 'values,' which as we saw last year include giving a tax cut to the wealthy while 80 percent of North Carolina families pay more," said Hagan spokeswoman Sadie Weiner, in response to the new ad.

Updated at 12:41 p.m.