“The walls are closing in,” The Washington Post quoted a senior Republican as saying. “Everyone is freaking out.” As that happens, and as some conservative voices cheer for Mueller’s ouster, I fear that Trump may replicate the 1973 Saturday Night Massacre and fire Mueller — and presumably a couple of layers of officials in between.

Nixon did this in 1973, firing special prosecutor Archibald Cox and provoking a national bellow of outrage that I remember well, even though I was then a 14-year-old Oregon farm boy. Both houses of Congress were then in opposition hands, providing honest oversight, and the firing of Cox eventually led to Nixon’s ouster.

What’s different this time is that both houses of Congress are controlled by the same party as the president, and I fear that if Trump fired Mueller the result would be less a bellow than a squeak.

Some Republicans earlier backed bills providing Mueller extra job security, but they now seem to have lost interest. The Times and others have suggested that if three Republican senators — Jeff Flake, John McCain and Bob Corker — pledged not to support legislation or judgeships, they could force Trump to back off, but I wouldn’t bet on that, either.

The reason for Republican reticence is simple: Trump still has 78 percent backing among Republicans, and senators like Flake who have challenged him have lost support. If you’re a Republican senator, I fear that your political interest may be to respond to Trump firing Mueller by calling for an investigation of Hillary Clinton. Governing is hard, so it can feel more rewarding to pretend that Clinton won and scream for her imprisonment. Indeed, Sean Hannity forgot himself and referred to her as President Clinton.

After Nixon fired him, Cox declared: “Whether ours shall continue to be a government of laws and not of men is now for Congress and ultimately the American people.”

That is our challenge now, and I hope we can all rise to it, Republicans and Democrats alike. That means not acting as cheerleaders for Mueller’s ouster and for a national crisis. That means insisting that Mueller’s investigation continue, unimpeded by firings or pardons. That means recognizing that there is something larger than party labels, and that is our adherence to laws and the pursuit of truth.

In 1973 we passed the test, and our institutions held; now we may face a similar crisis. It’s time for Congress to wake from its snooze and for citizens to brace themselves not to roll over, but to roar.