In Fox News interview, Trump almost confesses to obstruction of justice.

https://thinkprogress.org/trump-says-hes-willing-to-testify-under-oath-that-the-former-fbi-director-lied-to-congress-f1fecc75b2de

During a Rose Garden news conference on Friday, President Donald Trump said for the first time that he is “100 percent” willing to give a sworn account of his interactions with former FBI Director James Comey.

Trump also accused Comey of lying to Congess during his testimony on Thursday to the Senate Intelligence Committee — an offense that can land a person in prison for up to five years. Comey testified that Trump asked him to quash an active investigation into one of his associates in February, weeks after the president asked his former FBI director to pledge personal loyalty. Comey says he effectively ignored both of Trump’s requests, and was fired in May.

In response to Comey’s stunning testimony, Trump and his lawyer have staked out an incoherent position. They claim that Comey is a liar who provided Congress with an inaccurate account of his interactions with Trump, specifically with regard to former National Security Adviser Michael Flynn and the “loyalty pledge;” at the same time, however, they claim Comey’s testimony also totally vindicated the president because he indicated that Trump was not personally under investigation.

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http://www.thedailybeast.com/fox-and-friends-host-tells-trump-he-was-smart-to-threaten-comey-with-tapes

But when he found out that there maybe are tapes out there, whether it’s governmental tapes or anything else or who knows, I think his story may have changed.

...

But it was Earhardt’s follow-up that seemed to stun even the president. “It was a smart way to make sure he stayed honest in those hearings,” she said, sounding more like one of his sycophantic cabinet members than a member of the media.

“Well, uh, it wasn’t very stupid, I can tell you that,” Trump replied, a smile forming across his face. “He was, he did admit that what I said was right.

...

A couple of hours after Trump’s interview aired, White House Press Secretary Sean Spicer actually went on camera on Fox, where he insisted to anchor Bill Hemmer that Trump was in no way trying to “intimidate” Comey with his original tweet about tapes.

“The reality is, is that he wanted to make sure the truth came out,” Spicer said, “and by talking about something like tapes, made Comey in particular think to himself, ‘I better be honest, I better tell the truth about the circumstances regarding the situation.’”

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1. Comey's witness-account accuses Trump of trying to sabotage the Flynn-investigation. That's obstruction of justice.
2. Trump first calls Comey a liar.
3. Trump then claims that his tape-threat made Comey change his story, which is witness intimidation.
4. Trump then claims that Comey told the truth.
5. WH-spokesperson Sean Spicer then clarifies that Trump did not intimidate the witness. The goal was merely for the truth to come out.

Summed up:
Comey accused Trump of obstruction of justice. And Trump boasted that his tape-threat made Comey change his story from lie to truth.