Washington (CNN) After months of vowing to fight for his innocence, former Trump campaign chairman Paul Manafort conceded to committing several federal crimes and agreed to cooperate with the Justice Department, including in special counsel Robert Mueller's investigation of Russian interference in the 2016 presidential election.

Manafort pleaded guilty in federal court in Washington, DC, on Friday to one count of conspiracy against the US and one count of conspiracy to obstruct justice due to attempts to tamper with witnesses.

Friday's court activity signals Mueller's investigation will continue and delve deeper into what Manafort knows. Even in lessening the charges against Manafort, prosecutors still have significant leverage over him if he isn't helpful to their investigation.

Manafort's decision to cooperate with Mueller comes just weeks after President Donald Trump called Manafort a "brave man" who would not "make up stories in order to get a 'deal'" after he was convicted in a separate trial in Virginia.

He also admitted to all the other crimes Mueller accused him of since last October -- from money laundering and bank fraud to foreign lobbying violations related to his work for pro-Russian Ukrainians. Those charges will be dropped if he completely complies with the cooperation agreement.

"I plead guilty," Manafort said to the judge near the end of the hour-long hearing.

Special counsel's office senior prosecutor Andrew Weissmann told the judge that under Manafort's plea agreement, the other charges will be dropped after he is sentenced in both Virginia and DC "or at the agreement of successful cooperation."

Manafort was separately convicted of eight crimes by a Virginia federal jury last month. The 69-year-old now faces a likely prison sentence of almost 20 years when the two convictions are stacked consecutively.

But for now, his sentencing is on hold.

Manafort's cooperation deal means he will have to meet with the special counsel's office when they want to speak with him about other criminal activities, turn over all documents relevant to the investigation, testify when needed and never lie to them.

The terms don't prevent other parts of the Justice Department or state and local authorities from bringing new charges. He also could face administrative claims from the government, the agreement says.

"Your client shall testify fully, completely and truthfully before any and all Grand Juries in the District of Columbia and elsewhere, and at any and all trials of cases or other court proceedings in the District of Columbia and elsewhere," the plea agreement, which Manafort signed a day before, says.

Trump world reacts

While Trump is not mentioned in Friday's filing, nor is Manafort's role in his campaign, the news of the cooperation comes as the President continued to lambast the Mueller investigation on Twitter this week.

In a statement to CNN after the news of Manafort's cooperation, White House press secretary Sarah Sanders said, "This had absolutely nothing to do with the President or his victorious 2016 Presidential campaign. It is totally unrelated."

Wearing a purple tie beneath his dark suit, Manafort looked glum as the hearing unfolded, standing next to his attorney, Richard Westling, with a court security officer standing immediately behind him. Manafort answered the judge's questions about himself, his plea and rights he will waive, including his rights to a trial and to any appeals.

"I do," he said repeatedly in a soft voice, waiving each right. As a prosecutor read a long statement of what Manafort admitted to, Manafort sat near the courtroom wall with his eyes closed.

Kevin Downing, Manafort's lead attorney, said as he exited the courthouse that Manafort wanted to make sure that "his family was able to remain safe and live a good life. He's accepted responsibility, this is for conduct that dates back many years and everybody should remember that."

Manafort had proffered information to the government on Tuesday, and his legal team signed the deal on Thursday.

In recent days as the Manafort plea talks were ongoing, the President's legal team expressed confidence that if Manafort signed a cooperation agreement it wouldn't have anything to do with the President, according to a source briefed on their thinking.

In a statement Friday, the President's attorney Rudy Giuliani reiterated that confidence.

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

It was the second version of the statement. The initial version, which was quickly revised, included "Paul Manafort will tell the truth" as part of the quote. The amended version removed the phrase.

A legal source, supportive of the President and familiar with the Manafort case, said the Trump team does not believe Manafort has anything significant on the President to share with the special counsel.

The White House had previously distanced itself from Manafort and downplayed his time leading the Trump campaign. But last month, Trump expressed sympathy for him and encouragement that he hadn't flipped.

"I feel very badly for Paul Manafort and his wonderful family," the President tweeted the week of Manafort's conviction in his Virginia trial. "'Justice' took a 12 year old tax case, among other things, applied tremendous pressure on him and, unlike Michael Cohen, he refused to 'break' - make up stories in order to get a 'deal.' Such respect for a brave man!"

Full admission

In their filing, prosecutors describe Manafort's scheme to take in more than $60 million from pro-Russian Ukrainians and launder that money to avoid paying taxes. His admissions include his use of offshore bank accounts to move the money, deceiving his accountants and bookkeeper and then spending the money on lavish purchases and real estate.

He also admitted to lying to banks about his assets to gain millions of dollars in loans as a way to supplement his income, according to the filing.

"Manafort cheated the United States out of over $15 million in taxes," the filing states, adding that in order to commit the crimes, he relied on help from both his longtime deputy Rick Gates and the Russian Konstantin Kilimnik.

Generally, Manafort's guilty plea centers around his foreign lobbying crimes.

His plea filing gives extensive detail about his political work for the Ukrainians, specifically the Party of Regions and former Ukrainian President Viktor Yanukovych, whose government jailed a political rival and who now lives in exile in Russia. Manafort admits to his client group being a pro-Russian political party in Ukraine, the filing says.

Manafort used a politics center in Belgium, called the European Centre for a Modern Ukraine, as a "mouthpiece" for his Ukrainian clients, the filing says. The organization lobbied in the US and Europe, but "effectively ceased to operate" in 2014, when popular revolution swept Yanukovych out of power.

Manafort sought to prevent US legislators from imposing sanctions against Ukraine and condemning Yanukovych after the jailing of Yulia Tymoshenko, a political rival and former Ukrainian prime minister. At one point, Manafort pushed damaging stories about Tymoshenko in the US, including an allegation that she had "paid for the murder of a Ukrainian official," the court filing said.

Manafort said his "goal is to plant some stink on Tymo," according to the filing.

He and his subcontractors were paid more than $11 million for their work, which they did not disclose to the US federal government as required by law.

In a second illegal lobbying effort, Manafort assembled a group of influential former politicians in Europe -- including the former Austrian chancellor, Italian prime minister and Polish president -- to pose as independent voices before US lawmakers, when they in fact worked for Ukraine. Manafort directed them to be paid more than 2 million euros between 2012 and 2014, the filing said.

He also cultivated the former Polish president to push positions favorable to Ukraine in the European parliament, where the former president had oversight of Ukraine.

In 2012, Manafort orchestrated a supposedly independent report by the prominent US law firm Skadden Arps about the trial of Tymoshenko. He paid the firm largely out of his offshore accounts more than $4.6 million for its services, the filing said, while Yanukovych's government publicly said the report cost only $12,000. He also plotted a million-dollar public relations roll-out in the US of the report so that the report's news coverage did not condemn Yanukovych for selectively prosecuting Tymoshenko. Two of the public relations firms Manafort employed on Ukrainian issues lobbied Congress, the White House and the State Department, he admitted. He also personally met with a member of Congress on Yanukovych's behalf in 2013 -- telling his Ukrainian client afterward the meeting "went well," the plea filing said.

Manafort then lied to the Justice Department in September 2016 about his, Gates' and his consulting companies' work for Ukraine.

Other consequences

The proceedings Friday were the second time in under a month Manafort had faced his own guilt in court.

Even following his eight convictions in last month Virginia, Manafort still faced seven charges in Washington and another 10 possible charges in Virginia, which had been declared as mistrials after the jury hung on them last month.

Westling agreed in court Friday that 10 charges in Virginia on which the jury hung would be dropped later. In DC, his seven criminal counts are rewritten as two--amounting to significantly fewer penalties if he had pleaded guilty to his earlier indictment.

Manafort also agreed to forfeit millions of dollars in assets to the federal government.

In all, Manafort will hand over five properties, including his Trump Tower condo and mansion in the Hamptons, three bank accounts and a life insurance policy. The value of the bank accounts and life insurance policy are not yet known, and it's unclear how much money Manafort owes to banks after taking mortgages out on some of the real estate.

The combined value of the real estate he'll forfeit exceeds $22 million, according to prosecutors' descriptions and public records of property sales and tax assessments.

Manafort will return to jail following the hearing Friday.

No sentencing dates are yet set, though the prosecutors will update the court on his status in mid-November.

Jury selection was set to begin next week

Friday's plea deal preempts a trial that was set to start in three days with jury selection.

The strain of the trial loomed large, threatening to push Manafort, his extensive political connections throughout Europe and several people and companies among Washington's lobbying and law firm elite back into the spotlight.

As part of the run-up to the second trial, Manafort's lawyers filed hundreds of pages in court to fight prosecutors' allegations -- having brought two appeals unsuccessfully -- and his legal fees mounted to more than $1 million, according to two people familiar with his case.

Manafort, Trump's top political operative from May to August 2016, has long been considered one of the bigger fish for Muller's office. In addition to the financial and lobbying charges against Manafort, the special counsel's team had said previously it was investigating allegations he colluded with Russia while working for Trump.

Over the past several months, Manafort's legal options slimmed as the special counsel notched several wins against him, including sending him to jail, securing several cooperators and gaining convictions.

Manafort's case marked the first indictment in Mueller's investigation. The allegations revealed last October reiterated a year of news reports that Manafort had secretly funneled income from Ukrainian lobbying contacts for years.

After his arrest in October, he was detained by the court in his Alexandria, Virginia, home for more than eight months.

Then in February, prosecutors filed new mortgage and tax fraud charges against him weeks after they discovered he was offering to secure his bail with homes tied up in his alleged mortgage fraud.

Prosecutors also gained the cooperation of his longtime associate Rick Gates, who had been indicted alongside him. Gates pleaded guilty in February to helping Manafort use bank accounts in Cyprus and Grenadines to hide millions they had made while lobbying for Ukrainian politicians. Gates testified against Manafort in the Virginia trial, saying his former boss had directed him to commit the fraud.

The special counsel's office added a second potential cooperator against Manafort two weeks ago when another lobbyist for the Ukrainians, Sam Patten, pleaded guilty to a foreign lobbying charge. Patten worked with Manafort's Russian associate Kilimnik through 2017 and admitted in court to illegally using a straw purchaser to buy Trump inaugural tickets for an oligarch.

Kilimnik is charged as a co-defendant in Manafort's DC criminal case, for the witness tampering accusation. In previous court filings, prosecutors allege he had ties to the Russian GRU, a military intelligence agency. Kilimnik has not appeared in court, though Manafort's plea Friday admits that he committed his crimes in conspiracy with both Gates and Kilimnik.