WASHINGTON – Paul Manafort, the former chairman of President Donald Trump's campaign, pleaded guilty Friday to two felony conspiracy charges and reached an agreement to provide "complete cooperation" with special counsel Robert Mueller's probe of Russian interference in the 2016 election.

Manafort's plea deal brings investigators further into the president's inner circle of advisers and adds another conviction to their growing scorecard.

Wearing a dark suit, white shirt and purple tie, Manafort told U.S. District Judge Amy Jackson: "I plead guilty."

The 69-year-old former lobbyist and political operative acknowledged leading a long-running conspiracy involving his work on behalf of a pro-Russian faction in Ukraine led by the country's former president Viktor Yanukovych. He also pleaded guilty to obstructing the special counsel investigation he has now promised to assist.

The charges could send him to prison for more than a decade and will force him to surrender millions of dollars in bank accounts and real prime real estate, including a $3 million apartment in the president's namesake Trump Tower on Manhattan's Fifth Avenue.

Manafort's plea agreement makes him the latest Trump aide to cooperate with the investigation that has cast a shadow over the first two years of his presidency. And it suggests that investigators, who have now brought charges against four aides who served Trump on the campaign trail or in the White House, still have other targets in their sights.

Trump unconcerned, aides say

As recently as last month, Trump praised his former campaign manager, who he said said was a "brave man" who "refused to break." On Friday morning, however, that refusal came to an abrupt end. One of the prosecutors, Andrew Weissman, confirmed in court that Manafort was cooperating with the government's investigation.

Asked whether Manafort’s deal included an agreement to provide information related to President Trump, defense attorney Richard Westling said his client has pledged “complete cooperation.”

The agreement also is memorialized in court documents, requiring Manafort to cooperate with the government "in any and all matters as to which the government deems...relevant."

The implications of that agreement – including what investigators hope he will tell them, and about whom – were unclear. But Trump's advisers swiftly signaled that they were unconcerned.

"Once again an investigation has concluded with a plea having nothing to do with President Trump or the Trump campaign," Trump's attorney, Rudy Giuliani, said Friday. "The reason: the President did nothing wrong."

White House spokeswoman Sarah Sanders said Manafort's case "had absolutely nothing to do with the president or his victorious 2016 presidential campaign."

"It is totally unrelated," Sanders said.

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For months, Manafort had resisted taking the step he did on Friday, even as prosecutors piled on new felony charges and a jury in Virginia found him guilty of eight felonies. A separate trial on additional charges was due to start Monday in federal court in Washington.

Manafort's plea deal follows agreements that Mueller's team had already reached with Trump's former national security adviser Michael Flynn and Manafort's former deputy Rick Gates. Separately, Trump's former personal attorney, Michael Cohen, implicated him in a criminal campaign finance violation during his own plea hearing in federal court last month.

Manafort pleaded guilty Friday to conspiring against the United States for his work as an unregistered agent of Yanukovych's pro-Kremlin political faction in Ukraine, and of conspiring to obstruct justice by seeking to persuade two people who had helped with that work to offer inaccurate accounts to federal investigators.

Smear campaign in Ukraine

A sweeping 24-page statement of offenses cataloged a decade worth of criminal conduct, much of it centered on his work on behalf of the former Ukranian president, Yanukovych, now living in exile in Russia. Manafort, according to court documents, led a hardball political campaign in which he sought to smear Yanukovych's political rival, fromer Ukraine prime minister Yulia Tymoshenko, as a murderer and anti-Semite.

Manafort and his partners earned tens of millions of dollars for that work between 2006 and 2015, and stashed large portions of it in Cyprus bank accounts to shield it from U.S. tax authorities.

Prosecutors asserted that Manafort "knowingly" filed false income tax returns between 2006 and 2015, and failed to report more than $15 million in income between 2010 and 2014.

The charges replace a raft of separate accusations that Manafort had failed to register as a foreign agent, lied to the government, laundered money and committed fraud. In a court filing Friday, Mueller's office said Manafort laundered more than $30 million from his work for Yanukovych, then "used his hidden overseas wealth to enjoy a lavish lifestyle in the United States." The criminal conduct continued through 2017.

Assortment of allegations

As Manafort's plea hearing began, Weissman walked methodically through the assortment of allegations in a packed federal courtroom in Washington. When he finished, the judge asked Manafort whether it was all true, describing the allegations as one of the "longest" such recitations in her court.

"It is," he replied in a soft voice.

In addition to the criminal charges, prosecutors said in a court filing that Manafort could be forced to forfeit assets that would deal him a significant financial blow: four houses he owns, including an expansive retreat in the Hamptons, plus bank accounts and the proceeds of a life insurance policy.

Manafort’s lead attorney, Kevin Downing, said after Friday’s hearing that his client “accepted responsibility” and wanted to “make sure his family would remain safe and live a good life.”

Downing said that Manafort is committed to his cooperation agreement with the government, adding that a schedule of meetings already has been set.

Contributing: William Cummings and David Jackson of USA TODAY; Heath reported from McLean, Va.

See Manafort filing below: