That would include specifying that only a Senate-confirmed Justice Department official - which Whitaker is not - could dismiss Mueller.
But the Senate Republican leader gave no hint of support for Whitaker as a permanent replacement.
Donald Trump fired attorney general Jeff Sessions on Wednesday and appointed Whitaker, a former U.S. attorney from Iowa and Sessions' chief of staff, to be acting attorney general - a move Democrats called illegal.
In a separate interview past year with the Wilkow Majority on SiriusXM radio, Whitaker opined on the Mueller investigation, saying, "The truth is there was no collusion with the Russians and the Trump campaign".
On Friday, the Wall Street Journal reported that the FBI had opened a criminal investigation into World Patent Marketing, publishing an email that one victim of the company had received from a victim specialist for the bureau.
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What about for $350 million? Zack Greinke ($34 million), David Price ($31 million) and Clayton Kershaw ($31 million) all got more. Despite the presence of Harper and Manny Machado on the market, it seems the Red Sox have other, more pressing issues.
Whitaker's connection to the company "came as a surprise to both senior Justice Department and White House officials, several officials said".
He has also been pressing to interview Mr Trump on his 2016 campaign's ties to Russian Federation and allegations that he obstructed the investigation.
Democrats have pointed to Mr. Whitaker's past critical comments of the Mueller probe as proof he can't be in a position to impartially oversee it.
Whitaker has given no signs he plans to step back from the probe, saying he is "committed to leading a fair department with the highest ethical standards, that upholds the rule of law, and seeks justice for all Americans".
Democrats will specifically scrutinise whether Whitaker made any "commitments to the president about the probe", Schiff said on NBC. It appears that Whitaker is now overseeing the Russian Federation probe.
Whitaker, who is a former US attorney, previously served as Sessions' chief of staff. They were not authorized to speak publicly about private conversations and spoke on condition of anonymity.
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Schumer said he was concerned about the past statements Whitaker made as a commentator on CNN about the investigation.
Whitaker's conduct will determine whether he is remembered like Robert Kennedy-who overcame inexperience, a partisan background and close ties to the president to lead the department with distinction-or Harry Daugherty, Warren Harding's campaign manager and corrupt attorney general who helped cover up the Teapot Dome scandal.
Likewise, as Chief, I did not know Mr Whitaker except primarily as he traveled with AG Sessions. Matt Whitaker worked for Jeff Sessions, and he was always extremely highly thought of, and he still is.
"We've been compliant, it's going to go on, nobody's interrupting it or interfering with it", Conway said on ABC. "That also happens to be my view".
Paul Pogba and Romelu Lukaku set to miss out on Manchester derby
Meanwhile, Jesse Lingard was the link between midfield and attack, expected to chase down blind alleys in search of the ball. City are doing everything right, on the pitch at least, while United continue to flounder in search of a way forward.