Colorado’s Republican U.S. Rep. Ken Buck triggered a firestorm Wednesday when his grilling of former special counsel Robert Mueller showed that President Trump could face obstruction of justice charges when he leaves office.

Pundits have speculated that Buck didn’t expect Mueller’s response, unintentionally driving a narrative that House Democrats could use to push for Trump’s impeachment.

And Buck, a Windsor Republican who has largely flown under the radar during his years in Washington, found himself trending on Twitter.

Buck told Colorado Politics he had no regrets about his exchange with Mueller, saying that he isn’t “taking any heat” for it.

The former Weld County prosecutor and three-term congressman insisted that Mueller’s response only hypothetically established a time frame for a president’s immunity – during his term in office – and that Mueller did not “opine on whether the president committed a crime or not and would not opine on that.”

Here’s what followers of the hearing seized upon:

“Could you charge the president with a crime after he left office?” Buck asked Mueller at the House Judiciary Committee hearing Wednesday morning.

“Yes,” Mueller replied.

“You believe … that you could charge the president of the United States with obstruction of justice after he left office?” Buck asked again.

“Yes,” Mueller replied.

“Ethically, under the ethical standards?” Buck pressed further.

“Well, I’m not certain because I haven’t looked at the ethical standards, but the … opinion says that the prosecutor, while he cannot bring a change against the sitting president, nonetheless he can continue the investigation to see if there are any other persons who might be drawn into the conspiracy.”

Buck appeared to nod slightly as he was told his time had expired.

Mueller opened a Wednesday afternoon House Intelligence Committee hearing by clarifying his testimony from the morning’s hearing, during which Rep. Ted Lieu, D-Calif., asked Mueller, “The reason again that you did not indict Donald Trump is because of the … opinion stating that you cannot indict a sitting president, correct?”

Mueller answered: “That is correct.”

But later, Mueller said: “We did not reach a determination as to whether the president committed a crime.”

Buck said the later response changes everything about his exchange with the special prosecutor.

“He is not opining on whether the president committed a crime, and I think that’s unfair,” Buck said. “I think that’s his job.” 

In video tweeted by Vox.com journalist Aaron Rupar on Wednesday afternoon, Trump appeared to respond to the exchange between Buck and Mueller and the subsequent clarification, stating, in part, that Mueller “totally corrected himself in the afternoon.”

Buck countered critics who claim he asked a question without knowing the answer, a rookie mistake in legal circles. Buck said congressmen and lawyers have different jobs.

“The reason I ask questions is to get answers,” he said. “[It’s] different than a trial. We don’t have discovery in this situation. I didn’t talk to the witness beforehand.”

The state Republican party, which Buck heads as chairman, was mum on the congressman’s performance during the hearing.

The Colorado Democrats sarcastically cheered Buck’s questions at the hearing, saying that “it’s good for voters to know that Donald Trump could soon face legal consequences for his corruption after they vote him out of office in 2020.” 

“I would like to personally thank Ken Buck for confirming with Robert Mueller that President Trump could indeed be indicted and criminally charged with obstruction of justice after he is out of office,” state Democratic Party Chair Morgan Carroll.

Buck’s exchange with Mueller unleashed a hail of tweets, with Democrats thanking the staunch Republican, and pundits and media outlets highlighting the irony of the exchange.

“Thanks to Ken Buck, Mueller is now on the record saying that a sitting president can be indicted post-presidency for obstruction crimes,” Rolling Stone tweeted with a link to an article on the exchange.

“Did Ken Buck just get Mueller to confirm that Trump can be charged with crimes for what he’s done after he leaves office? A Republican did that?” tweeted Kevin Kruse, an author and professor of history at Princeton University.

Trump weighed in with his own take on the matter, tweeting Wednesday afternoon, “TRUTH IS A FORCE OF NATURE!”

From Weld County, Buck was elected chairman of the Colorado Republican party on March 30. He is a former district attorney who was responsible for halving Weld County’s crime rate, according to his congressional biography.

He additionally served as a prosecutor with the U.S. Department of Justice and as the chief of the criminal division at the Colorado’s U.S. Attorney’s Office, the biography says.

The Wall Street Journal and The Associated Press contributed to this report.

Editor’s note: This article was updated at 2:18 p.m. to attribute the Colorado Democratic Party’s quote to Morgan Carroll.