Sen. Susan Collins (R-Maine) on Friday renewed her call for the Senate to pass legislation that would protect special counsel Robert Mueller, following news that acting Attorney General Matthew Whitaker will oversee the Russian investigation.

"It is imperative that Special Counsel Robert Mueller be allowed to complete his investigation into Russian influence efforts during the 2016 elections," Collins said in a statement on Friday.

The GOP senator, who has previously supported passing a bill to protect Mueller, added that she's concerned by comments Whitaker has made about the special counsel and the "parameters of his investigation."

"For these reasons, I believe that we should bring to the Senate floor legislation that would put restrictions on the ability of President Donald Trump to fire the Special Counsel," she said Friday. "Senate debate and passage of this bill would send a powerful message that Mr. Mueller must be able to complete his work unimpeded."

Her comments come two days after Jeff Sessions resigned as attorney general at Trump's request. That same day, the president announced that Whitaker, Sessions's former chief of staff at the Justice Department, would serve as his acting replacement until an eventual nominee is confirmed.

Whitaker will have oversight of Mueller's investigation, a move that has drawn bipartisan scrutiny as a result of previous commentary from Whitaker.

"Mueller has come up to a red line in the Russia 2016 election-meddling investigation that he is dangerously close to crossing," Whitaker wrote in an op-ed for CNN in August 2017.

Senate Minority Leader Charles Schumer (D-N.Y.) and House Minority Leader Nancy Pelosi(D-Calif.) have called for Whitaker to recuse himself from overseeing the Russia probe.

Deputy Attorney General Rod Rosenstein had been overseeing the Russia investigation since 2017.

It remains unclear if he will step aside from helping with oversight, according to The Washington Post.

While Collins has said Mueller's probe should have certain legislative protections, Senate Majority Leader Mitch McConnell (R-Ky.) said Friday that such legislation is not necessary.

"The Mueller investigation is not under threat," he said. "The president said repeatedly that he's not going to dismiss the Mueller investigation. He's said repeatedly it's going to be allowed to finish."