Sen. Marco Rubio (R-FL) was one of Rex Tillerson's toughest interrogators Wednesday on Capitol Hill as the secretary of state confirmation hearing got underway. Many of Rubio's questions revolved around Tillerson's connections to Russia's Vladimir Putin.

"Is Vladimir Putin a war criminal?" Rubio asked the Exxon Mobil CEO. Has his military "violated the rules of war?" Are he and his cronies to blame for the murder of political dissidents and journalists? Rubio seemed to get louder and redder with each question, noting he was "concerned" by Tillerson's inability to give definitive answers.

Media put their recorders in front of Rubio after the hearing to ask whether or not he plans to vote for Tillerson.

"I'm prepared to do what's right," Rubio said.

The senator was hesitant about Tillerson's nomination at the get go. Shortly after Trump tapped the Exxon Mobil CEO in December, Rubio tweeted that he did not care to have a secretary of state who once claimed to be a friend of Putin's.

Being a "friend of Vladimir" is not an attribute I am hoping for from a #SecretaryOfState - MR — Marco Rubio (@marcorubio) December 11, 2016

Senate Minority Leader Chuck Schumer (D-NY) was also troubled by Tillerson's ties to Russia, as well as his failing to support sanctions against the country.