If we follow that educated guess to its logical conclusion, then it looks like Trump just tried to discredit Rosenstein, the official who appointed an independent counsel that is now investigating the president. If Trump ever wanted to get rid of an investigation that is targeted at him, discrediting the man who set it up would be a great way to do it.
Here, let me rephrase Trump's tweet for him so my argument makes a little more sense:
I am being investigated for firing the FBI director by the deputy attorney general, who told me to fire the FBI Director! Witch hunt!
A bit of background: Shortly after Comey's firing, Rosenstein appointed special counsel Robert S. Mueller III to lead a broad investigation into Trump campaign Russia ties and obstruction of justice. Almost daily since then, Trump has blasted the investigation as a “Witch Hunt!;" actually the greatest political witch hunt in the history of the nation.
As The Post's Philip Bump explains, Trump can end this “witch hunt” one of three ways. All carry serious consequences:
1. Just break all the rules, fire Mueller himself and face potential legal consequences.
Except: Anyone who's anyone in Washington has discouraged him from this. Last week, a friend of the president said Trump was considering firing him. The White House didn't deny this consideration, but they later said Trump has “no intention” of firing Mueller.
2. Get Rosenstein to do it. (That's how the regular order goes, assuming Attorney General Jeff Sessions keeps his promise to recuse himself from all things Russia.)
Except: Trump is probably very aware that Rosenstein testified to Congress last week that he would only fire Mueller for “good cause.”
3. Get rid of Rosenstein entirely and hope the person who takes his place agrees Mueller needs to go. (That's eventually how President Richard Nixon got rid of an independent investigator looking into him.)
Except: Just like Trump needs a reason to fire Mueller, he needs a reason to get rid of Rosenstein, too. Could blaming Comey's firing on him be that reason? It's possible Trump tested that out Friday.
“In order to try to attempt to raise a legitimate scenario to fire Mueller, Trump has to discredit him,” said Jeffrey Jacobovitz, a white collar lawyer who represented officials in the Clinton White House and now is with Arnall Golden Gregory LLP.
Trump has laid the groundwork for a controversial firing before. About a month before he fired Comey, Trump started throwing conspicuous shade at the FBI director, testing out an argument the White House would later use.
“Director Comey was very, very good to Hillary Clinton. That I can tell you,” Trump told Fox Business's Maria Bartiromo in April. “If he weren't she would be, right now, going to trial.”
Then, days before Trump fired Comey, he tweeted this:
When Trump finally fired Comey, he seemed to have been looking for an excuse to do it, The Fix's Aaron Blake noted at the time.
Ironically for Trump, firing Comey to get the pressure of the Russia investigation off him has only exacerbated the legal pressure he's under. Trump's go-to move is to try to cut it all off at the head. As I wrote Thursday: “When he feels backed into a corner, he lashes out in politically inadvisable ways that often makes his life much more difficult. But he can't seem to stop doing it.”
Friday's tweet — cryptically and possibly aimed at Rosenstein — would seem like one way for the president to test out how to get this “witch hunt” off his back.