David Leonhardt
David Leonhardt

Again and again over the past year, Mitch McConnell and Paul Ryan have had to decide what kind of behavior they are willing to tolerate from Donald Trump. Again and again, McConnell and Ryan have bowed down to Trump.

They have mumbled occasional words of protest, sometimes even harsh ones, like Ryan’s use of “racist” last year. Then they have gone back to supporting Trump.

The capitulation of McConnell and Ryan has created an impression — especially among many liberals — that congressional Republicans stand behind the president. McConnell and Ryan, after all, are the leaders of Congress, and they continue to push for the legislation Trump wants and to permit his kleptocratic governing.

But don’t be fooled: Republican support for the president has started to crack.

Below the leadership level, Republicans are defying Trump more often, and McConnell and Ryan aren’t always standing in their way. You can see this defiance in the bipartisan Senate investigation of the Russia scandal. You can see it in the deal on Russian sanctions. And you can see it in the Senate’s failure, so far at least, to pass a health care bill.

It’s true that we still don’t know how these stories will end. If the Senate passes a damaging health care bill or lets Trump halt the Russia investigation, I will revisit my assessment. For now, though, I think many political observers are missing the ways that parts of Trump’s own party have subtly begun to revolt.

Just listen to Trump himself. “It’s very sad that Republicans,” he wrote in a weekend Twitter rant, “do very little to protect their President.” In a historical sense, he is right. Members of Congress usually support a new president of their own party much more strongly than Republicans are now.

They typically understand that a young presidency offers the rare opportunity for sweeping legislation — like the Reagan tax cut, the George W. Bush tax cut, the Clinton deficit plan and the Obama stimulus, health bill and financial regulation. Some intraparty tensions are unavoidable, and defectors kill some legislation — as happened with the Clinton health plan and the Obama climate plan. But partisan loyalty is the norm.

Congress members tend to echo White House talking points fulsomely. They find the votes to pass bills. They defend the president against scandal. And the loyalty doesn’t stop in the first year. During Watergate, as the political scientist Jonathan Bernstein has noted, most Republicans stood by Richard Nixon until almost the bitter end.

Matt Glassman, another political scientist, is one of the sharper observers of the White House-Congress relationship, and I asked him to put the current situation in context. Glassman said that many progressives have made the mistake of comparing how they want Congress to treat Trump with what it is doing. The more relevant yardstick is how Congress’s treatment compares historically.

“The current congressional G.O.P. seems less supportive and more constraining of the Potus than basically any in history,” Glassman wrote to me, “save the unique circumstances of Andrew Johnson (who wasn’t really a Republican) and John Tyler (who bucked his party aggressively), neither of whom were elected.”

Many of today’s Republicans avoid going on television as Trump surrogates. They mock him off the record, and increasingly on the record, too. In recent weeks, eight senators have publicly stood in the way of a health care bill. Republican senators are also helping to conduct an investigation of Trump’s campaign and have backed the appointment of Robert Mueller as special counsel.

One reason is that they don’t fear Trump. About 90 percent of Republican House members won a larger vote share in their district last year than Trump did, according to Sarah Binder of George Washington University. Since he took office, Trump’s nationwide net approval rating has fallen to minus 16 (with only 39 percent approving) from plus 4.

So it’s not just Republican politicians who are inching away from Trump. Republican voters are, too.

None of this is meant to suggest that congressional Republicans have been profiles in courage. They haven’t been. They have mostly stood by as Trump has lied compulsively, denigrated the rule of law and tried to shred the modern safety net. But they have put up just enough resistance to keep him from doing far more damage than he otherwise would have.

In the months ahead, unfortunately, that level of resistance is unlikely to be sufficient. Trump has made clear that he isn’t finished trying to take health insurance away from millions of people or trying to hide the truth about his Russia ties. “The constitutional crisis won’t be if Trump fires Mueller,” as the A.C.L.U.’s Kate Oh put it. “The constitutional crisis is if Congress takes no real action in response.”

For now, anxious optimism — or maybe optimistic anxiety — seems the appropriate attitude.