President Trump’s silence lasted just over 12 hours. Then, he let it all out.

The appointment of a special counsel to investigate possible collusion between his campaign and Russia was the “single greatest witch hunt in American history,” he tweeted.

Hours later, during a news conference with Colombian President Juan Manuel Santos, Trump revisited the topic.

“I think it’s totally ridiculous. Everybody thinks so,” Trump said when asked about the appointment. “Everybody, even my enemies, have said there is no collusion.”

The comments underscore Trump’s seemingly unstoppable drive to combat an investigation that has dogged him since his first day in office — even if it prolongs the controversy and potentially puts him at greater legal risk.

(Victoria Walker,Jayne Orenstein,Dalton Bennett,Jenny Starrs/The Washington Post)

Trump has treated the Russia investigation as a public relations battle pitting him against his many enemies. But he has been slow to acclimate to new perils — particularly the legal ones — that seem to be mounting.

At nearly every opportunity, in interviews, tweets and public statements, Trump has insisted that the investigation is a politically motivated farce.

“James Clapper and others stated that there is no evidence Potus colluded with Russia. This story is FAKE NEWS and everyone knows it!” he tweeted in March.

In an interview in April with the Washington Examiner, he declared: “The Russia is a faux story. It’s made up.”

Meanwhile, the investigation has continued and is now criminal in nature, according to senators who were briefed by Deputy Attorney General Rod J. Rosenstein on Thursday.

Trump has never been one to shy away from prejudging the outcome of investigations. During the campaign, he and aides encouraged his crowds in chants of “Lock her up!,” demanding the conviction and jailing of Democratic presidential nominee Hillary Clinton in the investigation into her use of a private email server while she was secretary of state.

Trump has been dismissive of the seriousness of accusations he has made against others, including when he alleged without evidence that President Obama had wiretapped the phones in Trump Tower, an act that would have been illegal.

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But perhaps the greatest source of risk for Trump is in the allegation that in February he asked then-FBI Director James B. Comey to drop the investigation into former national security adviser Michael Flynn. According to Comey’s associates, Comey documented the comments in a memo written directly after he left the Oval Office meeting with Trump in February. And he prepared for meetings with Trump meticulously, concerned that the businessman president who has no previous political experience in Washington or with the law would push against legal and ethical guardrails.

Asked whether he had had such a conversation with Comey, Trump denied it flatly: “No. No, next question,” he told reporters during the East Room news conference Thursday.

A senior White House official said the president has been presented with options for retaining outside counsel in the case.

“The whole Comey situation, that’s a different ballgame,” said Alan I. Baron, who has served as special counsel to the House in impeachment proceedings against four federal judges. “It could well be treated as criminal interference into an investigation. Obstruction of justice.”

Trump’s propensity to discuss the case and Comey’s firing have only introduced more complications. In an interview days after firing Comey, Trump said that he was thinking of the Russia probe as he decided to do it.

In all, Baron said, while Trump maintains his First Amendment rights to free speech, most attorneys would strongly advise their clients against speaking about an ongoing case involving the clients or their associates.

“He would be a difficult client to serve,” Baron said. “If I’m representing somebody, you don’t say anything to anybody without talking to me first. That’s my first rule.

“If you can’t control yourself, just tell me where to send the flowers,” he added.

Many in the steady stream of headlines about the Russia investigation have been generated by Trump himself, making it more challenging for his administration to refocus on policy issues.

After firing Comey as FBI director, Trump suggested on Twitter that there might be “tapes” of his conversations in the White House that he would use to validate his account of his dealings with Comey.

The White House will not say whether Trump recorded conversations in the Oval Office. But the comments touched off immediate comparisons to President Richard Nixon — except that rather than keeping the possible existence of tapes a secret, Trump might have spoken publicly about them and opened himself up to future legal challenges.

“Nixon was much more circumspect than Donald Trump and, frankly, much more aware of what his own legal exposure was,” said Ken Hughes, a scholar at the University of Virginia’s Miller Center. “I was stunned when President Trump suggested that he might have tapes of his meetings with director Comey, because those would become the subject of subpoenas. They would be seen as evidence.”

“Nixon never publicly threatened people with his tapes, because he knew it would backfire on him,” said Hughes, whose areas of expertise include secret U.S. presidential recordings.

Publicly, according to Hughes, Nixon pledged cooperation with investigators even while he resisted handing over the tapes and privately fumed about efforts to sabotage his administration.

Trump has aired such grievances publicly on a nearly weekly basis, arguing that he is being treated unfairly by the news media and by his Democratic opponents.

Meanwhile, White House aides look hopefully toward the president’s upcoming foreign trip, which might help them shift the agenda back to firmer ground. But with nearly 30 million Twitter followers at his fingertips, Trump has resisted giving up his ability to battle the news media and investigators through a tool that he believes allows him to cut through the filter of the mainstream media.

“Donald Trump should start every morning with a tweet about what he is doing that day to help working-class Americans,” said Republican strategist Alex Conant. “Instead, his morning tweets make it clear how much the Russia story is distracting him and his White House.”