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Tom Coburn endorsed the Florida Republican senator in a statement Monday, the day before Oklahoma votes in its primary.

Calling his campaign a "fabrication," Coburn said Trump "is perpetuating a fraud on the American people."

Washington CNN —  

Marco Rubio picked up another high-profile endorsement Monday, this time from former Oklahoma Sen. Tom Coburn – who slammed front-runner Donald Trump for “fraud.”

Coburn endorsed the Florida Republican senator in a statement Monday, the day before Oklahoma votes in its primary.

He had harsh words for Trump, mirroring Rubio, who has also sharpened his attacks on the mogul.

Calling his campaign a “fabrication,” 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.”

It’s the latest big name endorsement for the Florida senator, who has locked up support from much of the Republican Party’s establishment names. In Oklahoma, one of a dozen states voting on Super Tuesday, Rubio also has the support of Sen. Jim Inhofe, Rep. Markwayne Mullin and former Gov. Frank Keating.

Coburn retired from the Senate in 2015 amid health problems. In the Senate, the conservative earned a reputation as a stiff budget-minded Republican who published a yearly “waste book” of government spending.

Quoting Martin Luther King Jr., Coburn said the time had come to support is former colleague.

“At a time when our republic, and the Republican Party, is at a crossroads I have no doubt that the right choice for America is Marco Rubio,” Corbun said. “America desperately needs a president who will appeal to people’s highest aspirations rather than their deepest fears; a president who will model servant leadership rather than self-promotion; and a president who will cast a vision and unite the country instead of denigrating dissenters as second-class citizens.”

And the former senator took multiple shots at Trump, saying his candidacy would undo the work of revered Republicans like Ronald Reagan.

“Put simply, Donald Trump has no plan to make America great again. He is a populist without portfolio,” Coburn said.