Republican U.S. Sen. David Vitter on Thursday morning endorsed Billy Nungesser, who is challenging incumbent Republican Lt. Gov. Jay Dardenne in the October elections.

“Billy is the true conservative in this race,” Vitter said of the Republican president of Plaquemines Parish. Nungesser, of Belle Chasse, is running to unseat Dardenne, of Baton Rouge.

“He’s not a RINO in any way,” Vitter said referring to the acronym for “Republicans in name only,” which some conservative members of GOP have used to criticize more moderate members of their party.