Marco Rubio Mum on Whether He Will Support Tillerson for Secretary of State After Human Rights Questions

— -- Sen. Marco Rubio, R-Florida, refused to tell reporters whether he will support President-elect Donald Trump’s nominee for secretary of state, after grilling him about human rights during today's confirmation hearing.

“I think it’s important, if you stand for moral clarity, that you be clear,” Rubio told reporters outside the hearing. "I'm prepared to do what's right."

Rubio’s comments could signal the first major roadblock for a Trump cabinet nomination.

Tillerson was pressed by Rubio on his positions on Cuba and Russia’s involvement in Syria. Rubio, a former rival of Trump’s during the 2016 presidential campaign, has been a critic of Trump’s friendly stance towards Russia.

Rubio also criticized Tillerson during the hearing for failing to label Vladimir Putin a war criminal as well as responses to questions about human rights transgressions in the Philippines, Saudi Arabia and China.

"I mean, it's clear that I'm concerned about some of his answers and encouraged by a few others," Rubio told reporters. "But obviously I want to go back and think through this a little bit."

Yesterday, Rubio and a bipartisan group of senators introduced legislation for sanctions against Russia for the country's suspected cyber attacks. President Obama has already taken action against what intelligence agencies call an influence campaign conducted at Putin's behest.

“If we're going to have moral clarity in our foreign policy, we have to be clear,” said Rubio. “And I don't want to see us move towards a foreign policy where human rights only matters when nothing else matters, when something more important isn't standing in the way.”

Rubio’s committee vote could impact whether Tillerson’s nomination proceeds to a full vote on the Senate floor. Rubio placed his hesitancy on the importance of the secretary of state role as the face of the United States around the world.

“He's been nominated to what I believe is the second most important post in the executive branch,” said Rubio. “And so I intend to take this very seriously.”

ABC News' Mary Bruce and Ali Rogin contributed to this report.<