A Republican candidate for the GOP Senate nomination in West Virginia ratcheted up his campaign attacks on Majority Leader Mitch McConnell, calling the Republican “Cocaine Mitch” in a new ad.

Don Blankenship, a former coal CEO who pleaded guilty to safety violations after an explosion killed 29 mine workers, had been in a tight race with state Attorney General Patrick Morrisey and U.S. Rep. Evan Jenkins for the Republican nomination to take on Sen. Joe Manchin III (D-W.Va.) in November.

But allies of McConnell (R-Ky.) formed a super PAC and began running ads targeting Blankenship’s past as leader of Massey Energy Co, at the time of the Upper Big Branch mine accident, the deadliest such coal incident in decades. Manchin is one of the top GOP targets this fall, and party strategists believe Blankenship would not win in a general election, given his background.

Blankenship, who was sentenced to a year in federal prison, has responded with personal attacks on McConnell, the most recent coming Tuesday in a Facebook ad in which he appears to cite an allegation from liberals that the family of McConnell’s wife, Transportation Secretary Elaine Chao, has a shipping background connected to drug dealers.

“One of my goals as U.S. senator will be to ditch ‘Cocaine Mitch,’ ” Blankenship says in the ad.

His campaign declined to comment, but the narcotics reference would appear to be a reference to a 2014 seizure of cocaine from a ship in Colombia bound for the Netherlands. Colombian officials seized 90 pounds of cocaine.

The ship came from the vast, sprawling maritime company founded by the Cabinet secretary’s father, James Chao, who emigrated from Taiwan. The incident received some attention after the Nation reported it in 2014, about a week before McConnell faced reelection — he won in a landslide — and has largely faded since.

But Blankenship, as he has slid in the polls, has made repeated attacks on Elaine Chao’s heritage. Last week, on West Virginia radio, he questioned whether McConnell had a conflict of interest because his father-in-law was a “wealthy Chinaperson.”

The GOP leader has largely ignored the attacks, and his allies think that the former coal CEO is unlikely to win the nomination. “My father-in-law is an American who lives in New York, works in New York, and I don’t have any comment about ridiculous observations like that,” McConnell said last week during a Fox News interview.

His office declined to comment Tuesday.

Blankenship’s campaign declined to comment on the rationale for the new ad. The primary is May 8.