Because there is no such thing as a slow news day in the Trump era, we learned today that Deputy Attorney General Rod J. Rosenstein, who oversees special counsel Robert S. Mueller III’s investigation into the Russia scandal, has offered to tender his resignation and has traveled this morning to the White House to discuss it with Chief of Staff John F. Kelly.

But make no mistake: This resignation, if it happens, is coming too late to save President Trump from Robert Mueller’s investigation.

The proximate cause of Rosenstein’s potential departure is a New York Times story reporting that Rosenstein suggested secretly recording Trump and recruiting members of the cabinet to invoke the 25th Amendment and remove Trump from office, though Rosenstein denied the story and another source said any comment about recording the president was sarcastic. Whichever version you believe, one thing is certain: Rosenstein, who has spent almost three decades as a Justice Department official and prosecutor, was not the kind of lackey Trump wanted in that position. In fact, it’s remarkable he lasted this long.

Let’s run down what happens now with regard to the Russia investigation. Rosenstein is supervising Mueller because Attorney General Jeff Sessions had to recuse himself from the matter, as a high-ranking official in the Trump campaign who had his own contacts with Russian officials in 2016. The president has made clear that he believes the job of the attorney general is to protect him from legal and political jeopardy; as he put it in a recent interview: “I don’t have an attorney general. It’s very sad.” But, unless and until Sessions is replaced — which many believe will happen after November’s election — responsibility for the Mueller investigation falls down the chain of command.

While Trump might replace Sessions and seems likely to replace Rosenstein, both of those positions require Senate confirmation. Not only does that take some time, but also when it happens, the nominees will without question be grilled about whether they plan to fire Mueller and if they had any communication with Trump or anyone else in the White House about that possibility. By being so public and obvious about his desire to have Justice Department leadership that would quash the investigation on his behalf, Trump has made it almost impossible for anyone he appoints to be in a position to do the one thing he seeks from them.

But in any case, permanent replacements for Rosenstein and possibly Sessions wouldn’t be in place for weeks or even months. In the meantime, responsibility for the investigation would fall to Solicitor General Noel Francisco. Which may give Trump hope, because Francisco is a movement conservative who is just the kind of Republican lawyer from whom Trump might expect loyalty.

But that is no guarantee. Francisco might well refuse to fire Mueller, realizing that doing so would set him down in history as a key player in a blatant attempt to obstruct justice by halting an investigation into the president’s misdeeds for no reason other than that the president doesn’t want to be held accountable. He might even recuse himself from the Russia investigation because his former law firm, Jones Day, represents the Trump campaign.

But wait, there’s more. While the law is a little murky, it may be that if Rosenstein resigns, Trump can immediately replace him with a new acting deputy attorney general (who could then fire Mueller), while if Rosenstein is fired, he can’t. As of this writing, there are conflicting reports about what Rosenstein is actually thinking and has said: NBC says he will refuse to resign, while the Post reports that “Rosenstein has told White House officials he is willing to resign.”

But we have to remember that if one way or another Trump can find someone to fire Mueller, it would be a political crisis even more dramatic than most of the ones he has already created. Every newspaper and TV news program would be talking about impeachment. If his aides have succeeded in convincing him not to fire Sessions, they may well be able to convince him not to order Mueller’s firing.

And it’s probably too late anyway. If this were all happening a year ago when the Mueller investigation was still getting off the ground, firing the special counsel might have done the trick. But at this point, Mueller and his team have done an enormous amount of work — and gotten guilty pleas and cooperation from five of Trump’s former aides (though his personal attorney Michael Cohen is cooperating not with Mueller at the moment but with the U.S. attorney in New York). Mueller may not be quite done, but he is surely close.

And given how meticulous they’ve been, it would be a shock if Mueller and his team haven’t prepared for the eventuality of being shut down. Perhaps they’ve kept a running, frequently updated report outlining everything they’ve found, a report that would one way or another find its way to the public. I’m guessing that if Democrats take over the House in November as everyone expects, they’ll use their power to subpoena documents and witnesses to do everything they can to bring the information assembled by the Mueller team to light.

Let’s keep in mind that because Mueller was never going to prosecute a sitting president, the danger he posed to Trump was always political. At this point, if Trump engineered Mueller’s firing, the political fallout would probably be worse than just letting him finish his investigation. So once again, Trump is trapped.