Special Counsel Robert Mueller has widened the Russia probe and is examining whether President Trump attempted to obstruct justice, the Washington Post has found.

This new tentacle of the year-long FBI investigation, now being handled by Mueller, unfolded days after FBI Director James Comey was fired by Trump on May 9.

Comey testified last Thursday that he believed he was axed as a way to trip-up the Russia probe saying, 'It's my judgment that I was fired because of the Russia investigation. I was fired, in some way, to change – or the endeavor was to change the way the Russia investigation was being conducted.'

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Special Counsel Robert Mueller (left) is reportedly looking into whether President Trump (right) obstructed justice, as his Russia probe expands

Comey also said Trump had pushed him to stop looking into former National Security Advisor Michael Flynn.

'I hope you can see your way clear to letting this go, to letting Flynn go. He is a good guy. I hope you can let this go,' Trump said, according to Comey.

Now Mueller's team wants to talk to others who were reportedly pressured by Trump on the issue.

Five sources told the Post that Director of National Intelligence Daniel Coats, NSA Director Mike Rogers and his ex-deputy Richard Ledgett agreed to be interviewed by Mueller's investigators.

The sit-downs could come as early as this week, the Post said.

The interviews suggest that Mueller, an ex-FBI chief himself, sees the 'he said, he said,' currently going on between Comey and Trump to be a bigger deal than just that, one of the Post's sources said.

The NSA told the paper it will 'fully cooperate with the special counsel,' while the office of the Director of National Intelligence and Ledgett declined to comment.

'The FBI leak regarding the president is outrageous, inexcusable, and illegal,' a spokesman for Trump's personal attorney Marc Kasowitz read.

It didn't challenge the accuracy of the Post's report.

The FBI probe was originally supposed to examine Russian meddling during the 2016 election, but had already expanded to looking into whether there was coordination between the Russians and the Trump campaign.

Comey's public admission of the latter, on March 20 before the House Intelligence Committee, rattled Trump and he asked the then-FBI director to make it clear publicly that the president wasn't personally under investigation.

Comey refused.

Trump then went to Coats and Rogers, making the same request.

Officials told the Post that Mueller is interested in conversations that took place on March 22, when Coats was less than a week on the job.

Coats was at the White House attending a briefing when Trump asked him, and CIA Director Mike Pompeo, to hold back.

Coats told the Post's sources that the president had requested that he ask Comey to get the FBI to back off of the investigation into Trump's ex-National Security Advisor Michael Flynn.

A day or two later, Trump called Coats, and also Rogers, and asked them to say publicly that there was no coordination between Russia and the Trump campaign.

The Post previously reported these exchanges, including that Trump's request was doubly denied.

Ledgett's involvement is unclear, though the Post's sources say he penned an internal NSA memo documenting Trump's call with Rogers.

When speaking before Congress last week, Coats said he never felt 'pressured' when interacting with the president.

Rogers said he wasn't 'pressured' either.

'In the three-plus years that I have been the director of the National Security Agency, to the best of my recollection, I have never been directed to do anything I believed to be illegal, immoral, unethical or inappropriate,' he told members of the Senate Intelligence Committee last Wednesday.

Neither official would say whether Trump made the ask.

That's a question that Mueller's team can ask, and that Coats and Rogers likely can't escape from in the long run.

Even though the White House can invoke executive privilege, the Supreme Court ruled during Watergate that government officials can't use privilege if they're withholding evidence in a criminal prosecution.