A GOP senator wrote a bill to protect Robert Mueller. Trump called him to try to kill it.

Since Special Counsel Robert Mueller was appointed to head the Justice Department’s Russia investigation back in May, Washington has speculated about whether President Donald Trump will end up firing him.

And according to a new report from Politico’s Josh Dawsey and Elana Schor, the president still seems to badly want to keep that option open.

Dawsey and Schor write that shortly after Sen. Thom Tillis (R-NC) introduced a bill that would let Mueller appeal his firing in court, Trump called up Tillis, signaled he was “unhappy” with the bill and said he didn’t want it to pass.

Tillis is a first-term senator who hasn’t been particularly known as a moderate or really for taking any high-profile stances at all. So it was a bit surprising when, earlier this month, he co-wrote a bill with Sen. Chris Coons (D-DE) to protect Mueller from Trump, and went on television to tout it.

Justice Department regulations already state that the special counsel can only be fired for “good cause,” but Tillis and Coons’s bill — the Special Counsel Integrity Act — would make that regulation the law of the land. It would also state that the special counsel could only be fired by a Senate-confirmed official.

Perhaps most importantly, the bill would also let a special counsel appeal his firing in court. If judges find that the firing was improper, the special counsel would be reinstated.

On August 6, Tillis appeared on Fox News Sunday and said there was “no question” that the bill was designed to prevent Trump from improperly firing Mueller. He also appeared on ABC’s This Week and said he wasn’t sure that he agreed with Trump that the Russia investigation was a “witch hunt.”

Trump called Tillis the next day to communicate that he didn’t want the bill passed.

Considering that President Trump already fired the FBI director in connection with the Russia investigation, there’s long been speculation that he might end up firing Mueller too.

And right now, it appears he could — but it wouldn’t be easy, and would likely cost him much of his Justice Department (in addition to, of course, creating an enormous political controversy).

Per Justice Department regulations, only the attorney general can fire the special counsel — and only for “misconduct, dereliction of duty, incapacity, conflict of interest, or for other good cause.”

Due to Attorney General Jeff Sessions’s recusal from all campaign-related investigations, though, the person who has the responsibility of firing Mueller is Deputy Attorney General Rod Rosenstein. (Trump’s unsuccessful effort to pressure Jeff Sessions into resigning this summer was likely motivated in part by his desire to get in a new, hand-picked attorney general who would not be recused from the Russia investigation. But, for the time being, this has failed.)

In congressional testimony in June, Rosenstein said he interpreted the regulation to mean that he is the only person in government with authority over Mueller’s hiring and potential firing — meaning not Trump and not Sessions. Furthermore, Rosenstein testified that he would only fire Mueller for “good cause,” and would refuse to carry out an order to fire him if good cause were not established.

But that doesn’t mean Mueller’s safe. That’s because Trump has the authority to fire Rosenstein himself. Rosenstein also could choose to resign if Trump orders him to fire Mueller without good cause. Indeed, like President Richard Nixon once did during the Saturday Night Massacre, Trump could repeatedly fire Justice Department officials until he has someone in place who would fire Mueller.

The Tillis-Coons bill would solve this problem by allowing the courts to reappoint Mueller if they deem his firing to be improper. And, it seems, Trump really doesn’t want that bill to become law.