UPDATE 9:12 p.m. EST: Sen. Marco Rubio spent the majority of Wednesday grilling former ExxonMobil Rex Tillerson on issues spanning Cuba, Russia, and Saudi Arabia.
Rubio's supposed dissatisfaction with Trump's secretary of state nominee could have far-reaching consequences. The Senate Foreign Affairs Committee, which presides over the secretary of state confirmation, only has a one-vote majority. That means if Rubio were to vote against the businessman, Tillerson's Cabinet posting could be in jeopardy.
"This is a very important decision and I recognize the partisan split on the committee and what it means," Rubio said after the hearing. "I'm prepared to do what's right."
UPDATE 2:55 p.m. EST: Sen. Rubio directed a second round of questions Tillerson's way during his Senate confirmation hearing. This time the Florida lawmaker focused on the Obama administration's revised foreign policy regarding Cuba.
When asked if he would advise President-elect Trump to veto a bill aimed at lifting the U.S. embargo on Cuba, Tillerson replied, "If confirmed, yes, I would."
Tillerson provided a vague answer when asked whether Cuba should be on the list of state sponsors of terrorism.
UPDATE 1:45 p.m. EST: New Jersey Sen. Cory Booker became the first sitting lawmaker in Senate history to testify against a sitting senator seeking Cabinet confirmation.
"I do not take lightly the decision to testify against a Senate colleague," Booker said. "But the immense powers of the attorney general combined with the deeply troubling views of this nominee is a call to conscience."
UPDATE 1:03 p.m. EST: Former 2016 presidential candidate Marco Rubio, R-Fl., wasted no time when it was his turn to question Tillerson. Right off the bat, Sen. Rubio asked whether Tillerson believed Russian intelligence services directed a campaign of active measures to undermine faith in the American political process.
Tillerson said he read the report, calling it "troubling."
Rubio's grilling of Tillerson continued with whether the former ExxonMobil executive would support additional sanctions against Russia.
Sen. Rubio then pivoted to focus the conversation on Vladimir Putin. He asked whether Tillerson would describe Putin as a war criminal.
"I would not use that term," Tillerson replied.
Rubio: Well, let me describe the situation in Aleppo and perhaps that will help you reach that conclusion. In Aleppo, Mr. Putin has directed his military to conduct a devastating campaign. He's targeted schools, markets, not just assisted Syrians in doing it, his military has targeted schools and markets and other civilian infrastructure.
Rubio vehemently disagreed.
"Well, let me describe the situation in Aleppo and perhaps that will help you reach that conclusion," Rubio said. "In Aleppo, Mr. Putin has directed his military to conduct a devastating campaign. He's targeted schools, markets, not just assisted Syrians in doing it, his military has targeted schools and markets and other civilian infrastructure."
UPDATE 10:38 a.m. EST: Tillerson said sanctions affect American business, which led to Sen. Bob Menendez (D-N.J.) to outline the utility of sanctions as a foreign policy tool.
UPDATE 10:34 a.m. EST:
When Sen. Marco Rubio asked Tillerson about the Russian hacking report released last week, Tillerson called the report "troubling," but did not say whether or not he believed Russian President Vladimir Putin carried out the attack.
He also said he would not call Putin a war criminal based on Russia's actions in Aleppo, which Rubio called "disappointing." He later said some of Putin's actions would constitute war crimes if proven.
The confirmation hearings for President-elect Donald Trump's cabinet picks continue Wednesday. The star of the show: Secretary of State pick Rex Tillerson, former CEO of ExxonMobil, whose hearing begins at 9 a.m. and is expected to last two days, according to United Press International.
Elaine Chao, Transportation Secretary nominee and former Labor Secretary, has a hearing scheduled for 10:15 a.m.
However, Tillerson, with his expansive business empire that has ties to Russia, is expected to be much more controversial.
Senators will be looking closely at how Tillerson responds to Russia's involvement in the Democratic National Committee hacks.
"Bottom line is, if you don't want to do anything about what Russia did, if you don't believe they're a good candidate for additional sanctions, I think a lot of people are going to look at you as not having the judgment for the job," Sen. Lindsey Graham (R-S.C.) told reporters.
The Associated Press contributed to this report.