Marco Rubio picked up two more endorsements Monday, from a prominent House Republican and another former Mitt Romney backer.

The Florida senator and Republican presidential candidate’s first endorsement came Monday morning, when Rep. Darrell Issa, R-Calif., ex-chairman of the House oversight committee, announced his support for Rubio on “Fox & Friends.”

“Marco Rubio really is an exciting candidate, and I’m pleased to be able to endorse him and to work for him for the presidency,” Issa said.

Michigan construction magnate John Rakolta also voiced his support for Rubio in a letter obtained by Fox News. The letter was sent to Rubio supporters and Rakolta’s influential national business network, which includes leaders in the Mormon commmunity. 

"I had the opportunity to meet with Marco Rubio one-on-one earlier this year for about an hour at a conference we were both attending in Park City, Utah," Rakolta wrote in the letter, referencing meeting Rubio at Romney's annual E2 Summit  in Utah. "I was immediately struck by his grasp of the issues, his willingness to listen and push back when he didn't agree with my point of view. Articulate and confident, he represents a new breed of Republican leader who can unite our party and win both the primary and general elections.”

Rakolta -- CEO and owner of Walbridge, a billion-dollar company -- is the third major backer from Romney’s 2012 bid to publicly endorse Rubio in the last several weeks. The others are billionaires Paul Singer (who also supported Rubio's Senate bid in 2010) and Frank Vandersloot.