WASHINGTON — Paul Manafort shared Trump campaign polling data with an associate tied to Russian intelligence during the 2016 campaign, prosecutors alleged, according to a court filing unsealed on Tuesday.
The accusations came to light in a document filed by Mr. Manafort’s defense lawyers that was supposed to be partly blacked out but contained a formatting error that accidentally revealed the information.
Prosecutors for the special counsel, Robert S. Mueller III, broke off a plea agreement with Mr. Manafort in November, accusing him of repeatedly lying to them. The details of their accusations have been kept largely secret until now.
In one portion of the filing that Mr. Manafort’s lawyers tried to redact, they instead also revealed that Mr. Manafort “may have discussed a Ukraine peace plan” with the Russian associate, Konstantin V. Kilimnik, “on more than one occasion.”
Investigators have been questioning witnesses about whether Russia tried to influence the Trump administration to broker a resolution to hostilities between Russia and Ukraine. Various “peace plans” were proposed, including at least one that called for the lifting of American sanctions against Russia. Mr. Manafort and Mr. Kilimnik had worked closely together for years on behalf of Russia-aligned Ukrainian interests.
Prosecutors have also accused Mr. Manafort of misleading them about his contacts with senior administration officials, about a payment from a pro-Trump political action committee made to cover his legal expenses, and about how he and Mr. Kilimnik tried to influence the testimony of witnesses to ward off criminal charges.
In their filing, Mr. Manafort’s defense lawyers said that Mr. Manafort never intentionally misled federal authorities. Instead, they blamed a faulty memory, lack of access to his own records and illness for his mistakes, saying their client has gout, depression and anxiety.
But they said that they would not seek a hearing to challenge the prosecutors’ assertions Mr. Manafort lied, a decision that brings Mr. Manafort one step closer to being sentenced for his crimes. He was convicted last year of 10 felonies including conspiracy to obstruct justice and failure to disclose years of lobbying work for pro-Russia oligarchs in Ukraine.
The decision not to seek a hearing reflected the dearth of legal choices for Mr. Manafort, 69, who led Mr. Trump’s campaign during a crucial period in mid-2016, then became a prime target of Mr. Mueller’s team. One prosecution in Northern Virginia resulted in his jury conviction in August for bank fraud, tax fraud and other financial crimes. A second led to his guilty plea in September on two conspiracy charges.
He agreed then to assist federal prosecutors in any matter they deemed of interest, including the special counsel’s investigation of Russia’s interference in the 2016 presidential election and the Trump campaign. He met 12 times with prosecutors or investigators from the special counsel’s team and from other offices, traveling from a detention center in suburban Washington where he has been held in solitary confinement since June.
The plea agreement gives the prosecutors the power to almost unilaterally decide whether Mr. Manafort has violated it. Unless Mr. Manafort can show they acted in bad faith — a high bar — their judgment stands. The prosecutors could also decide to file new charges against Mr. Manafort for lying to them, but do not plan to do so, according to the defense lawyers’ filing, unsealed Tuesday.
“They have him so deeply in the soup here that what both sides are almost saying is that this doesn’t matter,” said Nancy Gertner, a Harvard Law School professor.
The new filing came one month after Judge Amy Berman Jackson said in Federal District Court in Washington that she needed to know more about the prosecutors’ latest accusations against Mr. Manafort before she sentenced him on two conspiracy charges, which carry a maximum penalty of five years each. Judge T.S. Ellis III in Northern Virginia will sentence him for the other eight felonies.