The Russia investigation led by Special Counsel Robert Mueller has now extended to the finances and business dealings of Jared Kushner, according to The Washington Post. Chuck Schumer, D-N.Y., wrote his own letter, insisting that Rosenstein's hard-earned reputation as an "apolitical actor" was "now imperiled" by the deputy attorney general's role in Comey's firing.
Once Comey was sacked, the Department of Justice appointed Mueller as special counsel to act as an independent investigator.
Also Wednesday, Senate Judiciary Chairman Charles Grassley said his panel will investigate the removal of former FBI Director James Comey and "any alleged improper partisan interference in law enforcement investigations".
The president complained the probe is unfair and wondered why his defeated Democratic opponent wasn't getting the same scrutiny.
The problem for Trump - and Congressional Republicans - is that Mueller's investigation is going to take time.
In testimony on Capitol Hill last week, Comey said Mueller had a copy of that memo and several others Comey had written about his interactions with Trump.
Trump lashes out at 'bad,' 'conflicted' Russia investigators
Marc Kasowitz, Trump's personal lawyer, said Comey's testimony vindicated that Trump wasn't under investigation by the FBI. The first time he told Trump was in his first meeting with the president before the inauguration on January 6.
Robert Mueller, the special counsel named by the department to investigate the Russian Federation matter, is now examining whether Trump or others sought to obstruct the probe, a person familiar with the inquiry said on Thursday.
She said that Rosenstein "has been part of the Justice Department for 30 years and is such a respected person".
Dianne Feinstein, top Democrat on the Senate Judiciary Committee, said she was "increasingly concerned" that Trump will fire both Mueller and Rosenstein. Americans should be skeptical about anonymous allegations.
The Post, less than a month ago, reported Kushner was under FBI "scrutiny" in the Russian Federation investigation. Moscow denies meddling in the campaign.
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The Trump tweets come after the top lawyer for his transition team warned organization officials to preserve all records and other materials related to the Russian Federation probe.
"After seven months of investigations and committee hearings about my 'collusion with the Russians, ' nobody has been able to show any proof. Sad!" he wrote in one post.
Earlier tonight the Post reported Vice President Mike Pence has retained private counsel to help him in the Russian Federation probe. Mr. Pence's office confirmed he had retained Richard Cullen, a former Virginia Attorney-General and US attorney for the Eastern District of Virginia, to assist "in responding to inquiries" from Mr. Mueller. And in an indication that the investigation is widening its breadth and scope, members of the transition team were ordered to preserve documents related to the investigation, according to The New York Times.