WASHINGTON — President Trump started shouting on Twitter before 7 a.m. on Wednesday, venting about what he called the “Greatest Witch Hunt in U.S. history” as Robert S. Mueller III, the special counsel, was headed to Capitol Hill to testify in the Russia inquiry.
[Live updates: Robert Mueller’s Testimony Before Congress]
By 8:10, the president had posted seven more times, delivering a kind of Twitter greatest hits — punctuated by capital letters and exclamation points — in which he portrayed himself as the innocent victim of an illegal crusade by Mr. Mueller, Democrats and the country’s intelligence community.
He said that his accusers were part of an “illegal and treasonous attack on our Country.”
He complained again about the “18 angry Democrats” he asserted were on the Mueller team and asked why the special counsel did not investigate “Lyin’ & Leakin’ James Comey,” the former F.B.I. director whom Mr. Trump fired, and others.
The president attacked Mr. Mueller’s credibility, repeating his unsubstantiated claim that the special counsel was “highly conflicted.”
In all caps, he said: “NO COLLUSION! NO OBSTRUCTION!” and “KEEP AMERICA GREAT!”
On Tuesday, Mr. Trump had shrugged off the impending testimony, telling reporters that he would not watch the hearings on Wednesday, then admitting that “maybe I’ll see a little bit of it.”
But the president’s early morning online activities betrayed his real intentions, indicating once again that Mr. Trump appeared consumed by the investigation that had dominated much of his presidency.
Mr. Trump’s tweets have been a central part of the campaign by the White House and Mr. Trump’s Republican allies to condemn Mr. Mueller’s investigation and call into question the credibility of the special counsel, the F.B.I. and several of the intelligence agencies.
The effort was designed as a shield against just the kind of moment Mr. Trump found himself on Wednesday, watching along with the rest of the country as Democrats broadcast the investigation’s findings of wrongdoing.
From the moment the hearings began on Wednesday, the president’s allies in Congress made clear that they intended to take up his mantle, slamming Mr. Mueller and Democrats for wasting time and money.
But Mr. Trump has no intention of letting others defend himself while he remains silent.
In one of his early-morning tweets, the president complained about Mr. Mueller’s last-minute request to have one of his top lawyers accompany him during the testimony on Wednesday. Mr. Trump cast the request in a conspiratorial light, referencing claims by Republicans of misdeeds in the case of Hillary Clinton’s personal email server.
[Who is Aaron Zebley, the aide sitting beside Mr. Mueller?]
His focus on Ms. Clinton’s emails was a continuation from a tweet on Tuesday night. “What’s this all about? His lawyer represented the “basement server guy” who got off free in the Crooked Hillary case,” Mr. Trump wrote. “This should NOT be allowed. Rigged Witch Hunt!”
Wednesday morning, Mr. Trump appeared to threaten Mr. Mueller with prosecution for lying to Congress if the special counsel claimed during his testimony that he did not apply for the job of F.B.I. Director the day before he was appointed to lead the Russia probe.
“Hope he doesn’t say that under oath in that we have numerous witnesses to the interview, including the Vice President of the United States!,” Mr. Trump said on Twitter.