If the president can browbeat Rosenstein into resigning—or even plausibly misrepresent the firing as a resignation—Trump gains the power to bypass the Senate confirmation process under the Federal Vacancies Reform Act. He can replace Rosenstein with any serving official previously confirmed by the Senate to any other job.

The issue “Did he resign or not?” is likely to end up being adjudicated by the Senate Judiciary Committee—the same body that has proven itself so uninterested in getting to the true bottom of the allegations against Trump’s nominee to replace Justice Anthony Kennedy on the Supreme Court, Brett Kavanaugh…

But those past confusions were motivated usually by spite or vengefulness. This time, the highest political and constitutional issues are at stake. If Trump can sell the claim that Rosenstein resigned, he can buy himself substantial impunity for many months—months in which the GOP may lose control of the Senate altogether. By the time a new Senate can reassert authority over the Department of Justice, the Mueller investigation may be long dead.