Story highlights Marco Rubio was one of a few Republicans who had been withholding support for Rex Tillerson

Rubio's support virtually ensures Tillerson will win OK from the Senate Foreign Relations Committee

Washington (CNN) Sen. Marco Rubio, a key vote on the Senate Foreign Relations committee, said Monday he will vote for Donald Trump's choice for secretary of state, all but guaranteeing former oil CEO Rex Tillerson is confirmed as the US chief diplomat.

"Given the uncertainty that exists both at home and abroad about the direction of our foreign policy, it would be against our national interests to have this confirmation unnecessarily delayed or embroiled in controversy," Rubio said in a statement posted to his Facebook page. "Therefore, despite my reservations, I will support Mr. Tillerson's nomination in committee and in the full Senate."

Rubio's support virtually ensures that Tillerson will win approval from the Senate Foreign Relations Committee later Monday and sets him up for a full Senate approval at some point soon after.

Through the past weekend, Rubio was one of just three Senate Republicans who had been withholding support for Tillerson over broad concerns about his ties to Russian President Vladimir Putin. But the two other holdouts -- Sen. John McCain and Sen. Lindsey Graham -- said Sunday they would support Tillerson.

Rubio's decision comes after intense lobbying by the Trump administration, including a 90-minute meeting last week between Rubio and Tillerson, according to a Rubio adviser.

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