Paul Manafort, President Donald Trump's former campaign chairman, leaves the federal courthouse in Washington. A status hearing was scheduled Friday for Manafort amid reports that he was nearing a plea deal to avoid trial next week on charges stemming from work he did for pro-Russia political forces in Ukraine.

WASHINGTON — President Donald Trump's former campaign chairman Paul Manafort agreed Friday to cooperate with the special counsel's Trump-Russia investigation as he pleaded guilty to federal crimes and avoided a second trial that could have exposed him to more time in prison.

The deal gives special counsel Robert Mueller a key cooperator who steered the Trump election effort for a pivotal stretch of the 2016 presidential campaign. The result also ensures the investigation will extend far beyond the November congressional elections despite entreaties from the president's lawyers that Mueller bring it to a close.

It is unclear what information Manafort is prepared to offer investigators about the president or that could aid Mueller's investigation into Russian interference in the 2016 election. But his involvement in key episodes under scrutiny, and his leadership of the campaign at a time when prosecutors say Russian intelligence was working to sway the election, may make him an especially valuable witness.

The agreement makes Manafort the latest associate of Trump, a president known to place a premium on loyalty among subordinates, to admit guilt and work with investigators in hopes of leniency.

Manafort had long resisted the idea of cooperating even as prosecutors stacked additional charges against him in Washington and Virginia. Trump had saluted that stance, publicly praising him and suggesting Manafort had been treated worse than gangster Al Capone. Trump's lawyer, Rudy Giuliani, had suggested a pardon might be a possibility after the investigation was concluded.

Then came Friday's extraordinary development when Manafort agreed to provide any information asked of him, testify whenever asked and even work undercover if necessary.

Mueller has already secured cooperation from a former national security adviser who lied to the FBI about discussing sanctions with a Russian ambassador, a campaign aide who broached the idea of a meeting with Russian President Vladimir Putin; and another aide who was indicted alongside Manafort but ultimately turned on him. Trump's former personal lawyer has separately pleaded guilty in New York.

Friday's deal, to charges in Washington tied to Ukrainian political consulting work but unrelated to the campaign, was struck just days before Manafort was to stand trial for a second time.