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.