"I am ready to take a position," Merkley, an Oregon Democrat who serves on the Foreign Relations Committee, which heard Tillerson's testimony Wednesday, said in an interview on CNN's "New Day." "I'm going to vote against him, absolutely against him."
"It was a very disappointing performance yesterday," he added of Tillerson's day-long confirmation hearing. Merkley said he was disappointed with Tillerson's answers to questions about Russia and his time as CEO of ExxonMobil.
"Obviously, sanctions are a big concern -- as leader of Exxon, Tillerson proceeded to utilize a subsidiary to bypass American sanctions on Iran. His company lobbied extensively to get rid of the sanctions and certainly not to extend them," Merkley said, referring to charges that during Tillerson's term as CEO, ExxonMobil skirted US sanctions in international business dealings.
Tillerson said during his confirmation hearing that he did "not recall" such business dealings
Merkley also said he was surprised when Tillerson told the Senate committee that he hadn't discussed Russia policy with President-elect Donald Trump yet.
"That has not yet occurred," Tillerson said.
"It's inconceivable, because he's been very close to (Russian President Vladimir) Putin, the President-elect has been very close to Putin, Exxon had huge interests in Russia. And one of the reasons that you would think that Trump selected him is because he is very close to Putin, and so it didn't seem like he was speaking in a straightforward manner," Merkley said.
Still, Merkley said that one has "to give (Tillerson) credit" for his answers about Russian hacking.
"I said, 'If a candidate conspired with an outside country to take down your opponent in an internal election, wouldn't this be against the very core of our democratic process?' And he said, 'Yes, yes it would be.' So I have to give Tillerson credit on that one."
Republicans have a one-vote margin on the Foreign Relations Committee, meaning that if all Democrats on the panel and just one Republican vote against Tillerson's nomination, it will stall in committee. At least one Republican on the committee, Sen. Marco Rubio, is undecided. However, if the nomination does not make it out of committee, it is still possible for Senate GOP leaders to bring it to a vote before the full Senate, although such a step would be unusual.
Arizona Sen. John McCain told reporters Thursday he also has not yet made up his mind on Tillerson.