In some ways, Friday began like any other day. President Donald Trump fired up his Twitter app and sent off some defensive messages about the investigation into his campaign’s contacts with Russia, which has expanded to probe whether the president obstructed justice. But his series of tweets sent this morning reveals a grim reality for the White House: the president is running out of excuses.

In a series of messages, the president appeared to confirm that the Justice Department special counsel Robert Mueller’s investigation now includes whether Trump broke the law when he fired F.B.I. Director James Comey, from whom he allegedly attempted to extract a loyalty oath and a promise to go easy on his friend Mike Flynn. “I am being investigated for firing the FBI Director by the man who told me to fire the FBI Director!” Trump tweeted. “Witch Hunt.”

The message is a bit muddled, as intemperate tweets tend to be. It seems to refer to Deputy Attorney General Rod Rosenstein, who populated headlines after writing a letter highlighting Comey’s supposed flaws. Trump used that letter, along with an attachment by Attorney General Jeff Sessions, as cover for firing Comey on May 9.

With Sessions having recused himself from the probe, Rosenstein now technically oversees Mueller, and only he can directly fire the special counsel. On Friday, ABC News reported that Rosenstein was raising the possibility that he, too, would need to recuse himself from the matter, handing the D.O.J. investigation off to the department’s third-in-command. Trump’s contacts with Rosenstein, and the drama surrounding the Rosenstein letter, could prompt Mueller to call him in as a witness.

Blaming Rosenstein, as Trump did on Friday, stretches credulity, particularly because Trump himself said in a nationally televised interview on May 11 that he was going to fire Comey regardless of what Sessions, Rosenstein, or anybody else told him. “I was going to fire [Comey] regardless of recommendation,” he told NBC’s Lester Holt.

All this comes under the backdrop of Trump surrogates attacking Mueller’s credibility. Mueller, a decorated Vietnam veteran and the former director of the F.B.I., had been praised by Trump boosters. Newt Gingrich is, as ever, an illustrative example. A month ago, Gingrich tweeted that Mueller was “a superb choice” whose “reputation is impeccable for honesty and integrity.” After it was revealed that Mueller’s inquiry would include looking at potential malfeasance on Trump’s part, Gingrich decided that Mueller is actually “the tip of the deep state spear aimed at destroying or at a minimum undermining and crippling the Trump presidency,” and that Mueller is “the anti-Trump special counsel.” (On Friday morning, Gingrich reportedly claimed it was impossible for the president to obstruct justice. That should come as news to Bill Clinton, whom Gingrich, as speaker of the House, voted to impeach for that very reason.)

On Thursday, Trump tried to turn the negative attention, which he perhaps feels is contributing to his historically low approval rating, toward a familiar victim: “Why is that Hillary Clintons [sic] family and Dems dealings with Russia are not looked at, but my non-dealings are?”

Then he really went for it:

At this point, the president has accused the former F.B.I. director of lying under oath. He has publicly said he didn’t care about the recommendations of his attorney general and deputy attorney general. He continues to defend Mike Flynn, the disgraced former national-security adviser. He has undermined, on Twitter, his own Justice Department’s legal argument in multiple cases regarding his “Muslim ban” executive order. And now he is attacking the Justice Department for investigating matters that four congressional committees also find worth looking into.

Will he stop tweeting? It doesn’t look like it.