In his statement on Monday, Coburn said Trump is “perpetuating a fraud on the American people. His empty promises, bullying and bloviating rhetoric will only deepen the frustration and disillusionment that gave rise to his campaign. He simply lacks the character, skills and policy knowledge to turn his grandiose promises into reality.”

Coburn’s endorsement came a day before voters in Oklahoma and a dozen other states and territories head to the polls for Super Tuesday primary voting. Trump has led all polls in Oklahoma and visited the state for the second time last week.

Rubio hosted a rally in Oklahoma City on Friday and is scheduled to be there again tonight before going to Tulsa.

Coburn said Rubio “has been an extremely effective Tea Party senator. No candidate running for president has fought Obamacare more effectively than Marco and no one has a better grasp of foreign affairs and America’s place in the world.”