Two of Donald Trump's closest former advisers, Michael Flynn and Paul Manafort, are now "formally considered 'subjects' of a criminal investigation," just as the Department of Justice has finally appointed a special prosecutor to investigate the Trump team's ties to Russia.

Donald Trump and his team are in serious trouble now, thanks to relentless pressure from Democrats.

The Department of Justice has appointed former FBI Director Robert Mueller as special counsel to lead the investigation into Russia’s election meddling and the Trump campaign’s connection to that effort.

Mueller served under Presidents George W. Bush and Barack Obama and stepped down in September 2013.

In his letter announcing the appointment, Deputy Attorney General Rod Rosenstein wrote, “What I have determined is that based upon the unique circumstances, the public interest requires me to place this investigation under the authority of a person who exercises a degree of independence from the normal chain of command.”

The scope of Mueller’s investigation includes “any links and/or coordination between the Russian government and individuals associated with the campaign of President Donald Trump.” He will still be required to notify Attorney General Jeff Sessions ahead of any “significant actions” that he may undertake.

Sessions recused himself from the investigation after it was revealed that he lied to Congress about contacting Russia’s ambassador while he was a surrogate for the Trump campaign.

Trump responded to the news with a press release — he has not tweeted about it, at least not yet — in which he asserted, “There was no collusion between my campaign and any foreign entity.” He added, “I look forward to this matter concluding quickly.”

Trump previously said that the investigation “should be over.”

Citizens for Responsibility and Ethics in Washington Executive Director Noah Bookbinder called Mueller “the right man for the job” in a release, adding, “It is our sincere hope that he is able to get to the bottom of this situation — not just the truth about Russia’s interference with the 2016 election and any coordination it may have had with the Trump campaign, but also the truth about the president’s apparent obstruction of the FBI’s Russia investigation.”

The group has pursued lawsuits against Trump for violating the Emoluments Clause of the Constitution by continuing to take foreign payments as president.

The DOJ announcement comes as new reporting from NBC indicates that top Trump lieutenants Paul Manafort and Michael Flynn are emerging as key figures in the investigation. Law enforcement officials tell NBC that Manafort and Flynn “are formally considered ‘subjects’ of a criminal investigation.”

The FBI, Treasury Department, CIA, and other agencies are “examining evidence of possible contacts, money transfers and business relationships between a variety of Trump associates and Russian officials.”

The probe will also reportedly also investigate how Russian intelligence sources disseminated anti-Hillary Clinton fake news stories, as well as the leaking of hacked Clinton emails via WikiLeaks.

Manafort was the chairman of the Trump campaign until he was fired when news reports emerged about cash payments he had received from pro-Putin entities.

Flynn was an adviser to the Trump campaign and then briefly served as national security adviser. He was fired after it was revealed that he had lied about making contact with Russia.

According to a memo from former FBI Director James Comey, Trump asked him to cease investigating Flynn, which many are characterizing as an obstruction of justice. Trump later fired Comey, after Comey had reportedly asked for more resources to investigate Russian meddling and its Trump connection.

House Democratic Leader Nancy Pelosi cautiously praised the appointment of Mueller, calling it a “first step,” but insisting “it cannot be the last.” She noted that Mueller will still report to the “Trump-appointed leadership of the Justice Department” and “cannot take the place of a truly independent, outside commission that is completely free from the Trump Administration’s meddling.”

“A special prosecutor does not negate the need for vigorous Congressional investigations either,” Pelosi added.

Senate Democratic Leader Chuck Schumer said, “A special counsel is very much needed in this situation and Deputy Attorney General Rosenstein has done the right thing.”

Sen. Dianne Feinstein (D-CA), said the Mueller appointment was a “good first step.”

Rep. Ted Lieu (D-CA) praised those who have been pushing all along for a special prosecutor:

The resistance has demanded an independent investigation into Trump and Russia, and has been unrelenting in doing so. As several Democrats noted, the appointment of a special counsel is a good first step. But far more is needed to get to the bottom of what Russia did to interfere in our election, and how Trump’s campaign might have been complicit.