Aside from having all clashed with Trump last year, Rubio, McCain, and Paul have something else in common: They each secured another six-year term in November, meaning they won’t have to face voters again until after Trump runs for reelection in 2020. (Graham is up for reelection in 2020, too.) Their recent victories offer an extra measure of political protection from a Trump-inspired backlash, making it easier for them to oppose Trump as president even if he remains popular among Republicans. That dynamic doesn’t exist in the House, where Republican lawmakers have become increasingly sensitive to the possibility of a primary challenge every two years.

“Politically, if you’re in a ruby-red district, this is a president who’s going to be very difficult to oppose,” Representative Tom Cole of Oklahoma, a former head of the House GOP’s campaign arm, told me in a recent interview.

Rubio doesn’t have that worry, and even if he was on the ballot next year, he could point to the fact that his margin of victory in Florida was larger than Trump’s (although that was probably thanks to support from Democratic and Independent voters more than Republicans).

Political considerations, of course, would only be one factor in Rubio’s decision on whether to confirm Tillerson for a job that, as he told both the nominee and reporters, he considers to be the second most important in government, “with all due respect to the vice president.” Over three rounds of questioning on Wednesday, Rubio laid out a substantive case for the importance of human rights in foreign policy. He pressed Tillerson repeatedly to call out clear violations by Putin, Duterte, and by the government of Saudi Arabia in its treatment of women. In each case, Tillerson stopped short of issuing the unequivocal denunciations Rubio wanted, and at one point he called Tillerson’s reluctance to do so “discouraging.” When Rubio, citing the Russian-backed atrocities in Aleppo, asked him directly if Putin is a war criminal, Tillerson replied, “I would not use that term.”

The United States, Rubio told Tillerson near the end of the day-long hearing, needed to project “moral clarity” to the world. “We can’t achieve moral clarity with rhetorical ambiguity,” he said. Rubio then delivered an extended explanation of the questions he had asked Tillerson and why he felt so strongly about their importance for a candidate for secretary of state:

[The secretary of state] is the face of this country for billions of people, for hundreds of millions of people, as well, and particularly for people that are suffering and they’re hurting. For those people, those 1,400 people in jail in China, those dissidents in Cuba, the girls that want to drive and go to school, they look to the United States. They look to us and often to the secretary of state. And when they see the United States is not prepared to stand up and say, “Yes, Vladimir Putin is a war criminal; Saudi Arabia violates human rights. We deal with these countries because they have the largest nuclear arsenal on the planet, because China is the second largest economy in the world. Because Saudi Arabia is a strategic partner in what’s happening in the Middle East. But we still condemn what they do.” It demoralizes these people all over the world, and it leads people to conclude this, which is damaging, and it hurt us during the Cold War, and that is this: America cares about democracy and freedom as long—as long as it’s not being violated by someone that they need for something else. That cannot be who we are in the 21st century. We need a secretary of state that will fight for these principles. That’s why I asked you these questions. That’s why I ask those questions, because I believe it’s that important for the future of the world that America lead now more than ever.

Sensing that Rubio’s vote might be slipping away, Senator Bob Corker of Tennessee, the Republican chairman of the committee, used his closing remarks to appeal to Tillerson’s critics to give him the benefit of the doubt on the issue of moral “clarity.” “Senators,” Corker said, “develop pretty strong opinions, and sometimes, we express those opinions in a very crisp, direct, strong manner, just to break through the clutter that we have to deal with to make a point.”

A nominee coming in, on the other hand, wants to make sure that he’s not getting out over his skis. He’s working for a president that he doesn’t know that well yet. He’s trying to accommodate the fact that in fact he’s going to be working in an interagency situation to come to conclusions. So I just hope that those things will be taken into account if there are questions about clarity.

Will Rubio actually torpedo Tillerson’s nomination? A day later, he wasn’t saying. “Senator Rubio is working through this process, and we don’t have anything to announce at this time,” spokesman Matt Wolking said. He wouldn’t say whether Rubio planned to meet with Tillerson again before deciding how to vote.