Ben Roback is Head of Trade and International Policy at Cicero Group and a member of the US Embassy’s Young Leader’s UK programme.

Even in the current news cycle, one development can still pack a punch that makes everyone sit back in a moment of shock. Jaws dropped across Washington this week when it was reported that, in discussions with John Kelly, the White House Chief of Staff, Rod Rosenstein had verbally offered to resign amidst a tidal wave of criticism of Robert Mueller’s investigation from the top of the White House and Republican-supporting infrastructure around it.

Why Rosenstein’s potential exit is such a big deal

The chain of command at the Department of Justice (DoJ) has been the source of President Trump’s typically firebrand frustration for some time. When Jeff Sessions, the Attorney General, recused himself from the Russia probe last year, his deputy became the senior Justice Department official in charge of overseeing the investigation.

For a short period of time that was Dana Boente, while Rod Rosenstein, who now holds the post, was being confirmed by the Senate. Upon his confirmation by a comfortable 94-6 vote, Rosenstein became the second-ranking official at the Department, assuming the reins of the federal investigation into Russian interference in the 2016 election.

His exit would create a gaping hole in the department at a time when Mueller is increasingly encircling Donald Trump’s close associates. If the man in charge of the Special Counsel’s investigation is no longer in the building, who will assume control – and what might it all mean for Mueller?

Whilst the current situation remains fluid, we know for certain that Trump has always viewed the Special Counsel’s investigation as an awkward inconvenience that he would like to make disappear at the first available opportunity. Rosenstein’s resignation or firing, should either transpire, might present the president with a politically expedient opportunity to replace him with a friendlier face at the DoJ.

What next for the Mueller investigation?

The Special Counsel has maintained an unnerving sense of calm while carrying out his investigation so far, with no public attempts to push back on the president’s long list of tweets decrying a “witch hunt”. In procedural terms for the investigation, the circumstances of Rosenstein’s departure would be key. If he does resign, Trump has the power to select a replacement under the 1998 Federal Vacancies Reform Act, which states that, when an official resigns, the president is allowed to select an acting successor if the current officeholder “dies, resigns, or is otherwise unable to perform the functions and duties of the office.”

Note the omission of the term “fired”. Even then, Rosenstein’s replacement would assume responsibility as Deputy Attorney General, but not for the investigation. That would go to Noel Francisco, the Solicitor General.

In amongst fast-moving Washington politics, the Special Counsel might be tempted to speed up his investigation, in order to present his findings to Congress and the nation before being fired. But knee-jerk reactions have not been the style of Mueller so far; it is hard to see that changing even when the threat of firing looms large over his head.

Trump has never shied away from hiring, firing or tweeting in a moment of anger, regardless of the controversy or difficulty it might case his own White House. But facing the realistic prospect of a Democratic resurgence in the November midterms, it is hard to see how blowing up the Mueller investigation now would deliver any kind of political benefit for the president. Instead, it would more likely push Democrats into turning out to support candidates who pledge introduce emergency legislation to protect the Special Counsel.

Tomorrow, Rosenstein will meet Trump. The outcome of that meeting will have implications that reach far wider than simply the office of Deputy Attorney General. Meanwhile, as allegations of improper sexual behaviour against Brett Kavanaugh, the Supreme Court nominee Judge, build the news of Rosenstein’s potential exit could quickly become an afterthought.