CHARLESTON, W.Va. -- An election official has blocked former coal executive Don Blankenship's bid to run in West Virginia's U.S. Senate race as the Constitution Party's nominee.

News outlets report Secretary of State Mac Warner announced Thursday that he won't approve Blankenship's candidacy application, based on the state's "sore loser" law. The law prohibits major party primary candidates who lose from switching to a minor party. Blankenship finished third in the Republican primary.

Blankenship's campaign has said it will "vigorously challenge" any denial of his efforts to be on the November ballot with Republican Patrick Morrisey and incumbent Democratic Sen. Joe Manchin.

Blankenship is a former CEO of Massey Energy, which owned a mine where a 2010 explosion killed 29 miners. He spent a year in federal prison for violating safety regulations.