The diligence of congressional Republicans in holding Donald Trump’s presidency in check has so far inspired little confidence. Even some Republicans have been disappointed. “To carry on in the spring of 2017 as if what was happening was anything approaching normalcy required a determined suspension of critical faculties,” Republican Sen. Jeff Flake of Arizona wrote. “And tremendous powers of denial.”

All true. Yet this may be changing. Republicans are slowly, and perhaps even surely, beginning to use their constitutional authority to put some limits on a reckless presidency. It’s a shift that should be recognized — and encouraged.

Last week, before leaving Washington for their August recess, senators voted unanimously to hold pro forma sessions through the rest of the month. The move is inconvenient, requiring a senator to preside briefly every few days over an otherwise-empty chamber. But it was also crucial.

With Trump raging against Special Counsel Robert Mueller’s investigation into his affairs, the Senate made it impossible for Trump to fire Attorney General Jeff Sessions, a feared first step in targeting Mueller, and replace him with a recess appointment. Trump still could fire Sessions, but with the Senate officially in session, his replacement would require Senate confirmation, making it more difficult to install a chief law enforcement officer who is primarily concerned with protecting Trump.

In a related act of congressional defiance, both houses voted overwhelmingly in late July to sanction Russia for its attempts to influence the 2016 U.S. election, among other misdeeds. The vote was an unstated but obvious rebuke to Trump, who seems never to miss an opportunity to excuse Russian behavior. Meanwhile, two Senate Republicans are proposing separate bipartisan bills that seek to shield Mueller’s probe from meddling by Trump.

Noteworthy silences are on the rise, as well. Flake, a consistent critic of Trump, just published a book in which he condemned the “Faustian bargain” of appeasing the president’s dysfunction and affronts to the rule of law. Trump partisans attacked it harshly, but Flake’s Republican Senate colleagues didn’t.

“Under our Constitution, there simply are not that many people who are in a position to do something about an executive branch in chaos,” Flake wrote. “As the first branch of government (Article I), the Congress was designed expressly to assert itself at just such moments.”

Flake is right again. Members of Congress have unique powers, and this confers unique responsibilities. To minimize the damage from a turbulent presidency, Republicans need to accept those responsibilities, and discharge them.