Former Massey Energy CEO Don Blankenship, who finished third in the West Virginia Republican Senate primary, plans to run for West Virginia Senate as a third-party candidate.

Blankenship announced on Monday he’d run as the Constitution Party nominee, Politico reported. He said he’s willing to challenge the state’s “sore loser” law that would prohibit him from running in the general election since he already lost a major party’s nomination.  

Attorney General Patrick Morrisey won the GOP nod May 8 to take on Democratic Sen. Joe Manchin III in November. Inside Elections with Nathan L. Gonzales rates the race a Tossup. 

National Republicans had opposed Blankenship’s candidacy — with President Donald Trump even tweeting against him the day before the primary. Blankenship spent a year in prison for conspiring to violate mine safety standards at the Upper Big Branch Mine, where an explosion killed 29 people in 2010.