Barr's dance card included incoming Chairman Lindsey Graham, R-S.C.; outgoing Chairman Chuck Grassley, R-Iowa; and Nebraska Republican Sen.
"Barr must commit to supporting special counsel Mueller's investigation and allowing him to follow the facts", said Sen.
Ahead of Barr's Senate confirmation hearing next week, top Justice Department officials have sought to downplay his previous argument that the president can't be investigated for obstructing justice.
Rosenstein began overseeing special counsel Robert Mueller's probe into whether Russian Federation meddled in the 2016 presidential election when then-Attorney General Jeff Sessions recused himself in the matter over his role in Trump's presidential campaign.
Barr asserted that the president had been acting within his executive branch of authority when he made the request and said Mueller "should not be permitted to demand that the president submit to interrogation about alleged obstruction".
After ousting Sessions, Trump installed Whitaker, chief of staff at the Justice Department, as acting attorney general, which put him in charge of the Russian Federation probe.
Whitaker also was critical or skeptical about the special counsel investigation.
Rod Rosenstein, who appointed Special Counsel Robert Mueller to investigate Russian meddling in the US presidential election, is expected to leave the Justice Department after a new attorney general is confirmed, according to a person familiar with the matter. Rosenstein's departure has always been the subject of speculation. But Rosenstein disputed McCabe's characterization of the conversation.
A former USA attorney, Rosenstein expected to be fired back in September 2018 after a report surfaced that he offered to wear a wire during conversations with Trump.
It is not clear who Trump will nominate to fill Rosenstein's position.
Mr Rosenstein has yet to comment on the reports. Rosenstein has said the memo had no impact on the department's work.
He has accused the investigation of being led by "Democrat loyalists".
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