This would be for the good of the country, of course, because it might help avert a full-blown constitutional crisis. But it would also be to the benefit of the GOP and even Trump himself — though he might not be capable of appreciating that right now.

In an interview with me, Rep. Adam Schiff (Calif.) — the ranking Democrat on the House Intelligence Committee — argued strenuously that Trump’s pardon of Arpaio needs to be seen as a signal to those of his supporters who have been implicated in the Russia affair.

“The purpose for which the pardon was granted — to a political supporter of the birther movement — sends a message that if you have the president’s back, if you’re one of his supporters, he won’t necessarily wait until the end of a criminal case to give you a pardon,” Schiff told me. “He is telegraphing to anyone involved in his political campaign that as long as they stick with him, the possibility of a pardon is open, just the way it was for Arpaio.”

Trump pardoned Arpaio on Friday night, in advance of Arpaio’s sentencing, plainly aware that Hurricane Harvey would overshadow his act. At his Arizona rally, he suggested that “Sheriff Joe” had been convicted for “doing his job.” This is an implicit endorsement of the act that got Arpaio convicted of criminal contempt of court — refusing a judge’s command that he stop violating the constitutional rights of Latino immigrants. So perhaps Trump thinks Arpaio’s conviction was faulty. Meanwhile, Trump’s announcement of the pardon cited Arpaio’s alleged “service,” hinting that he deserves mercy. But neither argument has been elaborated upon. We have since learned that Trump had planned to pardon Arpaio, a campaign loyalist, well before there was any conviction, and that he viewed this as a way to please his base.

So Trump has offered no serious rationale for pardoning Arpaio. It is true that the pardon power appears absolute. But as multiple legal experts have pointed out, this particular use of it takes us into uncharted territory: Trump has signaled leniency toward law enforcement officials who refuse to obey judicial commands that they remain constrained by the Constitution, if they are loyal to Trump, or if his “base” will thrill to it. As Harvard’s Noah Feldman argued, Trump’s move appears to “threaten the very structure on which his right to pardon is based,” which risks “breaking the basic structure of the legal order” and constitutes an “abuse of the pardon power to break the system itself.”

And it could get worse. Schiff told me that the manner in which this pardon was done reasonably suggests it may be a signal to officials getting caught up in the Russia probe. “I don’t think it’s lost on anyone that the president is sending a message to those who worked on his campaign that he is not beyond using the pardon power to protect them and protect himself,” Schiff said. He added that Trump showed that “he’s willing to do it even prior to sentence,” which signals that he might be prepared to exercise it “to fend off any further criminal proceedings.”

“There are a number of ways that this could be applied to those who are either asking for immunity in the Russia probe or are exposed to potential liability,” Schiff said.

Grounds for impeachment?

Legal experts told me that if Trump were to do this, it could constitute grounds for impeachment — even if his legal power to do it is uncontested.

“If a president uses a pardon to buy the silence of a defendant or suspect in a criminal case, the witness will still go free,” Robert Bauer, a former White House counsel under Barack Obama, told me. “But the president could face impeachment. Congress is not bound by the requirements for formal legal liability: A High Crime as a basis for impeachment might overlap with the version in the legal system, but there is no requirement that it do. Congress makes its own determination in judging whether the president should remain in office.”

“Congress could pretty clearly use this as a basis for impeachment,” Martin Redish, a professor of constitutional law at Northwestern University, added in an email to me. “This isn’t just another controversial move by a controversial president. This is the first salvo in a war for the survival of American constitutionalism.”

Now, we do not know whether Trump will go through with something like this. We do not even know where special counsel Robert S. Mueller’s probe is heading. But the point is that members of Congress could be putting Trump on notice right now that if he does resort to such measures, Congress will not tolerate it.

“When it comes to this president’s trampling of our constitutional norms, silence is complicity,” Schiff told me. “People need to send a message to the president that the pardon power cannot be used as a way of preventing the implementation of justice when it comes to the Russia probe or any other.”

Schiff said that if a clear alarm is not sounded, the message Trump will get is that “he won’t face a political price or a constitutional crisis if he were to pardon anyone else who is a supporter of is, no matter what their violation may be.”

Obviously, Trump — who fired the FBI director over the Russia probe after reportedly demanding his loyalty, and publicly raged at his attorney general for failing to protect him from it — cannot be dissuaded from such a course of action via appeals to norms or to the rule of law or to any sense of obligation to the American public, which deserves a full accounting of the Russia affair. But Trump does appear to have a survival instinct of sorts that kicks in at moments like this: He reportedly was seriously considering trying to remove Mueller but was talked out of it by his staff.

And so, if Trump is persuaded that Congress will not tolerate it if Trump exercises pardons in the context of the Russia probe, perhaps he’d be less likely to go through with it, which could ultimately spare him from facing a congressional response. True, we can argue all day over whether Republicans actually would or wouldn’t impeach Trump if he went full authoritarian in this manner. But isn’t it in their best interests to do whatever they can right now to avoid a scenario in which they would be faced with this choice?