Comey had accused Trump of firing him to try to undermine the FBI's investigation of a possible collusion between the Trump Campaign and Russian Federation in alleged efforts to influence last year's presidential election.
That suggests Mueller is examining the president's own conduct, which may include whether Trump tried to obstruct justice. He said he didn't know if Trump obstructed justice, but said it was for Mueller to decide.
And on Thursday, the committee will hear testimony from Coats in a classified session - after he refused to say publicly last week whether Trump asked him to pressure Comey to back off Flynn. The Washington Post reported Wednesday that the investigators were looking into possible obstruction of justice.
It stands to reason that the circumstances surrounding Comey's firing would now be at the center of Mueller's query.
However, Mueller's investigation is in a relatively early phase, and it is unclear whether criminal charges will be brought when it is complete, U.S. officials familiar with the matter told The Washington Post on Thursday.
Mueller met Wednesday with the leaders of the Senate Intelligence Committee in an effort to ensure their investigations don't conflict.
NSA spokeswoman Vanee Vines told NPR's Phil Ewing, "NSA will fully cooperate with the special counsel". That showed that Trump is not one to be impeded by political protocol - Comey's 10-year term wasn't set to expire until 2023.
The probe into Kushner's business dealings is part of the special counsel's investigation into Russia's interference in the 2016 presidential election. He lashed out at a top Justice Department official overseeing the inquiry, reflecting his mounting frustration with the unrelenting controversy that has consumed his early presidency.More news: Pakistan's Mohammad Amir fit and plays in Champions Trophy final
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"No one outside the White House is contesting the fact that that is what happened, that director Comey is telling the truth", Seidman said. Kushner was also already under investigation for his secret meetings with several key Russian players, including Russian ambassador Sergey Kislyak and Russian banker and Putin spy Sergey Gorgov. The intelligence chiefs declined to discuss their private conversations with Trump during a Senate panel hearing on June 7. "That's Bob Mueller's job to sort that out".
Trump and his supporters cast Comey's testimony that he had told the president he was not personally under investigation as vindication. Pence headed the Trump transition until inauguration day. Comey said he found this troubling because the Federal Bureau of Investigation is supposed to operate independently of the president.
"Americans should exercise caution before accepting as true any stories attributed to anonymous 'officials, ' particularly when they do not identify the country let alone the branch or agency of government with which the alleged sources supposedly are affiliated", he said. But not everyone in the president's inner circle is trying to put out the fire.
Meanwhile, the White House said on Thursday that it would have no comment about the revelation, with deputy Press Secretary Sarah Sanders simply referring all questions to the President's personal lawyer, Marc Kasowitz. "Check FEC reports. Time to rethink".
Law enforcement sources tell CNN that the special counsel is gathering information and considering whether there is evidence to launch a full-scale obstruction investigation. "It's an investigation. You're talking to people to garner information".
Mueller's investigative team has expanded in recent weeks.
An obstruction of justice finding could form the basis for Mr Trump's impeachment but such a step would face a steep hurdle because it would require approval by the US House of Representatives, which is controlled by Mr Trump's fellow Republicans. Mueller's decision to talk with the two officials was reported earlier by the Washington Post. Why would the president object to a thorough investigation - unless he had something to hide?