Editor's note: This story has been updated with details of the Senate Foreign Relations Committee's vote.

WASHINGTON — Former Exxon CEO Rex Tillerson is almost certain to become the next Secretary of State, thanks to a lukewarm endorsement from the most pivotal senator in the confirmation process. 

U.S. Sen. Marco Rubio, a Florida Republican and member of the Senate Foreign Relations Committee, announced Monday morning that he would back the native Texan for the post as the chief American diplomat.

"In making my decision on his nomination, I must balance these concerns with his extensive experience and success in international commerce, and my belief that the president is entitled to significant deference when it comes to his choices for the cabinet," Rubio wrote. "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."

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"Therefore, despite my reservations, I will support Mr. Tillerson’s nomination in committee and in the full Senate," Rubio said. 

Tillerson officially won approval from the committee Monday evening, with 11 members supporting his nominations and ten opposing. The votes fell along party lines. 

Rubio's announcement came Monday after he eviscerated Tillerson during the nominee's confirmation hearing earlier this month, challenging him on human rights and on his ties to Russia.

Rubio could have thrown obstacles toward the nomination at the committee level. Two other key GOP senators, U.S. Sens. Lindsey Graham of South Carolina and John McCain of Arizona, announced Sunday they would back him

They, too, gave measured support. But the overriding sense among many of Tillerson's critics is that an alternative nominee could prove more problematic to their concerns. 

Disclosure: Exxon Mobil has been a financial supporter of The Texas Tribune. A complete list of Tribune donors and sponsors can be viewed here.

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