The line between actions and words is not as clear as it might seem. When Trump is considering some new policy or appointment and a senator like Flake says he will oppose it, those are just words. But they have seemed to constrain the president. For example, when Trump was hinting last year that he wanted to fire Jeff Sessions, the attorney general’s former colleagues in the Senate almost universally defended him and suggested that they would not confirm another Trump pick to run the Justice Department. Sessions remains.

When the White House said last week that it was considering allowing the Russian government to interrogate Michael McFaul, who was the U.S. ambassador to Russia under Obama, the Senate passed a 98-0 nonbinding resolution condemning the idea, which the administration had by then disavowed.

“I know a lot of people don’t put much stock into words, but I think they are more constraining of presidents than most people think, given how they shape public opinion and shape potential public reactions to future presidential actions,” said Matt Glassman, a congressional expert at the Government Affairs Institute at Georgetown University.