Details surrounding the agreement have yet to emerge.
Paul Manafort has reached a tentative plea deal with the special counsel Robert Mueller. Mueller's spokesman Peter Carr declined to comment on the possible deal, which was first reported by ABC News. It was the second time Manafort was denied moving a trial away from the Washington metropolitan area.
He would also likely face a tougher jury pool in politically liberal Washington than he did in the first trial, held in federal court in Alexandria, Virginia. Jurors deadlocked on ten other counts.
Prosecutors have previously said one of Manafort's close associates in Ukraine had contacts with a Russian intelligence agency.
Former Trump campaign manager Paul Manafort departs from U.S. District Court in Washington, U.S., February 28, 2018.
What isn't clear is whether Manafort might accept a deal in which prosecutors show leniency in exchange for cooperation.
Proceedings scheduled for September 17 would begin a second gruelling, expensive, politically explosive three-week-or-longer trial in federal court.
Trump Files Sanctions Order To Fight Election Interference
In a statement the Democratic National Committee said Trump's order "does nothing to hold Russian Federation accountable" for 2016.
Manafort's attorneys did not respond to TPM's email seeking confirmation of the joint defense agreement.
Following last month's verdict, a juror in the case told news outlets that the jury agreed to throw out Gates' testimony because they found him unreliable.
This trial, scheduled to start next month, concerns several counts of fraud and failure to register under the requirements of working as a foreign agent. He is also accused of tampering with witnesses in the case.
Although most of Manafort's charges predate his work for the Trump campaign, his conviction was still considered a huge victory for Mueller's Russian investigation - which Trump has exceedingly bashed and decried as a "witch hunt." The investigation also led to guilty plea by Trump's longtime personal lawyer, Michael Cohen, in a case brought by the USA attorney's office in Manhattan.
Jackson has yet to rule on how much jurors can hear about Manafort's contention that he is the victim of a selective prosecution.
The prosecutions of Manafort arose from Mueller's investigation into Russia's role in the 2016 US election and whether Trump's campaign colluded with Moscow to help him win.
None of the charges against Manafort related to collusion with Russian Federation.