With the midterms over, Washington returns to its regular programming: Russia. Trump critics should consider the risk of betting their political fortunes on special counsel Robert Mueller.

The Mueller probe has lost its political potency, as Democrats acknowledged on the midterm trail. They didn’t win House seats by warning of Russian collusion. They didn’t even talk about it. Most voters don’t care, or don’t care to hear about it. A CNN exit poll found 54% of respondents think the Russia probe is “politically motivated”; a 46% plurality disapprove of Mr. Mueller’s handling of it.

That hasn’t stopped Democrats from fixating on it since the election, in particular when President Trump fired Attorney General Jeff Sessions and named Matthew Whitaker as a temporary replacement. The left now insists the appointment is unconstitutional or that because Mr. Whitaker once voiced skepticism on the Russia-collusion narrative, he is unfit to oversee the Mueller investigation and must recuse himself.

The joke here is that neither Mr. Whitaker nor anybody else is likely to exercise any authority over Mr. Mueller—and more’s the pity. The probe has meandered along for 18 months, notching records for leaks and derivative prosecutions, though all indications are it has accomplished little by way of its initial mandate.

As a practical matter, Mr. Mueller should have been brought to heel some time ago. As a political matter, that won’t happen. The administration has always understood that such a move would provoke bipartisan political blowback, ignite a new “coverup” scandal, and maybe trigger impeachment. It’s even more unlikely officials would risk those consequences now, as Mr. Mueller is said to be wrapping up.