The special counsel Robert Mueller has reportedly begun compiling a final report of his findings in the Russia investigation.

The news raised questions from legal experts who wondered whether Mueller had moved up his timetable following President Donald Trump's decision to replace former Attorney General Jeff Sessions with Matthew Whitaker, a Trump loyalist who has publicly castigated Mueller and the investigation.

Whitaker reportedly will not recuse himself from the Russia probe or approve any request from Mueller to subpoena Trump.

Whitaker also has final say on whether Mueller's report sees the light of day.

The myriad questions surrounding Whitaker's independence prompted Department of Justice veterans and constitutional law experts to argue that Mueller has grounds to challenge Whitaker's appointment if he overrules a decision by Mueller.

The special counsel Robert Mueller’s team has begun writing a final report on its investigation into Russia’s interference in the 2016 election, CNN reported.

In addition to probing Russia’s election meddling, Mueller is also examining whether members of President Donald Trump’s campaign colluded with Moscow and whether Trump sought to obstruct justice after he learned of the investigation’s existence last year.

News of Mueller’s team working up a final report is not entirely unexpected. There’s long been speculation that the special counsel was holding off on making any big moves until after the midterm elections, because of DOJ guidelines barring investigators from taking any overt actions that could be seen as influencing the outcome of an election.

Still, the news raised questions among some legal experts, who wondered whether the special counsel had moved up his timetable following Trump’s decision to oust Attorney General Jeff Sessions on Wednesday. The president replaced the long-embattled Sessions with former US attorney Matthew Whitaker, a hardline loyalist who has publicly railed against Mueller and the Russia probe.

Read more: Justice Department confirms Jeff Sessions' replacement will take over the Mueller probe

Whitaker has reportedly been described as the West Wing's "eyes and ears" in the DOJ. He also said in a CNN op-ed last year that Mueller had overstepped his mandate by digging into the Trump Organization's finances. And The Daily Beast has reported the new acting attorney general made the rounds in right-wing media over the past two years claiming there was "no collusion" between the Trump campaign and Russian interests.

On Thursday, The Washington Post reported that Whitaker has no plans to recuse himself from overseeing the Russia investigation, despite his history of making antagonistic remarks about the special counsel.

Whitaker's appointment comes as Trump's lawyers are putting the finishing touches on their written answers to a first round of questions from Mueller about potential collusion. They are refusing to answer questions about obstruction of justice, and Mueller reportedly insisted on getting a chance to ask the president follow-ups as well.

On Thursday, CNN reported that as Trump was preparing to replace Sessions with Whitaker, the president had already begun reviewing the answers his lawyers had put together to send back to the special counsel.

It's unclear whether Mueller will accept the answers as is without pressing for an in-person interview.

If the special counsel wants to subpoena the president, he would need to get permission to do so from Whitaker. The Post reported that Whitaker would reject such a request.

As the person in charge of the investigation, Whitaker will also have final say on whether or not to make Mueller's report public.

The myriad questions surrounding Whitaker's independence prompted DOJ veterans and constitutional law experts to lay the groundwork for a legal argument saying Mueller could challenge Whitaker's appointment if he overruled a decision by Mueller.

Attorneys Neal Katyal and George Conway wrote in a New York Times op-ed that because a "principal officer" of the US must be confirmed by the Senate, "President Trump's installation of Matthew Whitaker as acting attorney general of the United States after forcing the resignation of [former Attorney General] Jeff Sessions is unconstitutional. It's illegal. And it means that anything Mr. Whitaker does, or tries to do, in that position is invalid."