The top super PAC for Senate Democrats is up with a new ad in North Carolina attacking Republican state House Speaker Thom Tillis, and it holds little back.

The Senate Majority PAC ad, which was shared early with The Washington Post, hits Tillis by highlighting two former staff members who were were engaged in inappropriate relationships with lobbyists, including one — his chief of staff — who shared an apartment with Tillis.

Tillis has said he wasn't aware of his chief of staff's affair, despite the two of them living together. The affairs were revealed in 2012, and Tillis was criticized for giving the staffers severance pay when they were forced to resign.

The ad buy is $973,000.

The ad is the latest in what promises to be a hugely expensive ad war in the Tarheel State. Conservative groups — most notably Americans for Prosperity, but also the Chamber of Commerce and American Crossroads and other groups — have dumped more than $10 million into the state already. (Correction: The Chamber has endorsed Tillis but hasn't run ads for him.)

The latter two groups have been supportive of Tillis, despite the fact that he faces a contested primary next month. Tillis is favored in the primary against Greg Brannon, a doctor who is backed by Sen. Rand Paul (R-Ky.), and pastor Mark Harris.

Senate Majority PAC and an allied group, Patriot Majority, have spent more than $4 million on Hagan's behalf, including the new buy.