In August, Manafort was found guilty on eight out of 18 counts of financial crimes in his first trial in Virginia.
"Manafort and his most senior defense attorneys spent more than four hours Thursday in discussions with a team of special prosecutors who are involved in the ongoing investigation into whether there was collusion between the Trump campaign and Russian Federation", the report says.
Another reason for Manafort to enter a plea - and the ABC News report reiterated this - is that Manafort would be spared exorbitant legal costs on a second trial that already appears likely to result in a guilty verdict, at least in part.
Mueller is investigating Russia's role in the 2016 US election and whether Trump's campaign colluded with Moscow to help him win.
"There's no fear that Paul Manafort would cooperate against the president because there's nothing to cooperate about and we long ago evaluated him as an honorable man", he added.
The report of a tentative deal comes days before jury selection is expected to begin for Manafort's trial in D.C., which is set to kick off with opening statements on September 24.More news: Kofi Annan Was An "Extraordinary Human Being" - Wife
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Jury selection is scheduled to begin in Washington, D.C., on Monday in Manafort's second trial in federal court on charges including conspiring to launder money and defraud the United States, and failing to register as a foreign agent for the tens of millions of dollars he earned lobbying for pro-Russian politicians in Ukraine.
Tuesday, there were reports that negotiations toward a possible plea deal were underway.
The tentative deal was first reported on Thursday evening by ABC News.
A pretrial conference scheduled for Friday morning, rescheduled late Thursday night.
Jackson said she would allow Downing to file additional information about his argument before issuing a ruling, but was inclined to bar such references because they weren't relevant to the charges against Manafort.
Manafort's second trial is expected to delve deeper into Manafort's Russian connections including to Konstantin Kilimnik, a Ukrainian-Russian political consultant who was indicted along with Manafort and who Mueller's team has linked to Russian intelligence.