Sen. Marco Rubio announced Monday morning he’ll back Rex Tillerson for secretary of State, essentially putting an end to questions about Tillerson’s confirmation prospects.

The Florida Republican announced his support for Tillerson in a Facebook post. But Rubio noted he still had concerns about Tillerson’s position on Russian aggression and human rights violations.

[ Eyes on Foreign Relations Panel Ahead of Rex Tillerson Vote ]

“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 wrote. “Therefore, despite my reservations, I will support Mr. Tillerson’s nomination in committee and in the full Senate.”

The Senate Foreign Relations Committee will vote on Tillerson’s nomination at 4:30 p.m. Monday. Tillerson’s nomination remained in question given concerns raised by Rubio and GOP Sens. John McCain of Arizona and Lindsey Graham of South Carolina. McCain and Graham announced on Sunday that they would back Tillerson.

Since Senate Democrats changed the rules in 2013, only a majority of senators are required to  end debate on an executive nomination.