Former acting White House chief of staff Mick Mulvaney said Wednesday that “things could get very dark” for ex-President Donald Trump as the House select committee investigating January 6, 2021, Capitol riot closes in on evidence that might lead to accusations of obstruction of justice.

In an op-ed article for USA Today, Mulvaney weighed in on a former White House aide’s testimony Tuesday before the Jan. 6 committee.

Mulvaney wrote that he had earlier defended Trump against claims that he did “anything illegal or criminal” in relation to the Capitol riot. However, now he was finding it difficult to maintain that position, especially after Cassidy Hutchinson‘s testimony, which he thinks is “eminently credible.”

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“Because after some of the bombshells that got dropped in that hearing, my guess is that things could get very dark for the former president,” Mulvaney wrote.

“The Jan. 6 committee members believe they have evidence that people within the Trump operation attempted to intimidate witnesses,” Mulvaney wrote. “And that, any way you slice it, is obstruction of justice.”

“Even if Donald Trump were as innocent as the virgin snow that Jan. 6, even if he didn’t know about the guns, or didn’t assault his agent, or had absolutely no clue what the Proud Boys were up to, if he obstructed justice related to the Jan. 6 hearings, then he could well become just the next politician to learn the hard lesson that it usually isn’t the crime,” he added. “It’s the cover-up.”

During Tuesday’s hearing, Hutchinson, who served as a senior aide to then-White House chief of staff Mark Meadows, detailed how Trump was full of anger the day he urged supporters to march to the Capitol. He was allegedly supportive of the Capitol attack.

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“I don’t f—— care that they have weapons,” Trump fumed before he addressed a “Stop the Steal” rally, Hutchinson testified. “They’re not here to hurt me. Take the f—— mags away.”

A Jan. 6 committee aide told NBC News in a statement: “The Select Committee found Ms. Hutchinson’s testimony to be credible. The committee welcomes anyone who wishes to provide additional information under oath.”

The evidence could be key as the committee is deliberately and intentionally laying out the building blocks for intent and premeditation.