In the wake of reports that President Donald Trump wanted to fire Robert Mueller last summer, only to relent when the White House counsel threatened to quit, Congress has shown renewed interest in legislation to protect the special counsel.

Democrats think such action is essential to keep the president from blocking the investigation of Russian interference in the presidential election. One proposal would require a three-judge panel to approve of any dismissal.

Republicans who refuse to go along may be accused of giving unwarranted cover to a reckless president. But they should refuse nonetheless. Passing such legislation would be a mistake for several reasons.

The first is that it intrudes on the authority vested in the executive branch by the Constitution, which gives the president responsibility for executing the laws. Federal prosecutors normally deal with all sorts of controversial and politically sensitive cases while answering to their superiors, in a system that fosters a due sense of priorities. Special prosecutors and special counsels, lacking the usual limits in latitude, are more likely to run out of control — as Kenneth Starr did, running a probe of Bill and Hillary Clinton that ate up six years and tens of millions of dollars but led to no charges against either.

It’s true that in 1988, the Supreme Court upheld a special prosecutor law against a constitutional challenge, but many experts doubt the court would rule the same way today. When Congress let that same law expire in 1999, writes Harvard Law professor Adrian Vermeule, it reflected “a bipartisan judgment ... that the Independent Counsel was a kind of constitutional Frankenstein’s monster, which ought to be shoved firmly back into the ice ...”

Testifying before the Senate Judiciary Committee last year, Yale Law professor Akhil Reed Amar, a Democrat who opposed Trump’s election, said the various proposals to block the removal of independent prosecutors, likewise “are unwise and unconstitutional.”

All this, of course, presumes that such a statute could be enacted. Even if the chronically deadlocked Congress were to approve this sort of legislation, Trump would certainly veto it, making the whole exercise little more than a spectacle of political theater.

More important, Congress has other ways to counter Trump’s desire to get rid of Mueller — notably impeachment. As Sen. Lindsay Graham, R-S.C., said last week, “We know that he didn’t fire Mr. Mueller. We know that if he tried to, it would be the end of his presidency.” No doubt White House counsel Don McGahn, who managed to dissuade Trump, made the same argument.

Barring some showing of misconduct, the president would be taking an enormous risk to cashier the special counsel. Congressional Republicans would not have the luxury of enabling such behavior. They would be risking mass immolation at the polls in November were they to let the president get away with firing Mueller.

In case Trump harbors any doubt, GOP lawmakers should let him know they won’t save him if he embarks on this self-destructive course. They could convey this in conversation, drop a note to the White House, maybe mention it in a tweet. Trying to pass a law protecting the special counsel would be a waste of time. Impressing on Trump the need to leave Mueller alone could be invaluable.