Most congressional Republicans haven’t said anything about Donald Trump’s controversial executive order banning refugees and residents of seven majority-Muslim countries from entering the United States. But a fair number, including a substantial group of senators, have spoken out and done so in a critical way.

They have not, however, taken any steps to get the order changed. This is noteworthy because right now individual senators are at a point of maximum leverage vis-à-vis the White House, which needs its Cabinet secretaries to be confirmed.

Today, for example, the senate is expected to take a vote to advance the nomination of Rex Tillerson to serve as secretary of state. Democrats, according to CNN’s Eric Bradner, “are now expected to push for the vote to be delayed until he comments on the Trump travel ban on refugees and citizens of seven Muslim-majority countries.”

It would only take three Republican senators joining them to force Mitch McConnell to give in and grant this request. That would create an opportunity for senators to get the designated secretary of state to clarify the order, and one for the Trump administration to alter the substance of the order to smooth things over. It would also lay the groundwork for potential tripwires on future Trump nominees to undersecretary positions.

Some Senate Republicans, of course, face the problem of being less popular with their own constituents than Trump is. But anti-order Republicans John McCain and Rob Portman were just reelected by much wider margins in their states than Trump secured. Susan Collins has criticized the order and represents a state Trump lost. Orrin Hatch, also critical, is from Utah, where Trump’s performance was catastrophically bad for a Republican.

The presidency is, at the end of the day, both the most powerful political office we have and one whose formal powers are rather circumscribed. The president can’t even staff his own administration without the Senate’s say-so. If the Republican senators who say they want Trump to modify this order insist that he modify it, he would ultimately have no choice but to do so. So far, though, they haven’t chosen to use the leverage they have. And once Trump’s team is in place, that leverage will diminish.

Watch: Donald Trump's executive order, explained