Paul Manafort is reportedly hitting the brakes on cooperating with Mueller

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Paul Manafort

• Talks between the special counsel Robert Mueller and former Trump campaign chairman Paul Manafort have reportedly broken down in recent days.
• According to the terms of his plea agreement, Manafort is required to cooperate in any and all matters the government deems relevant.
• The reported breakdown in talks comes as President Trump ousted Attorney General Jeff Sessions and replaced him with Matthew Whitaker, who frequently slammed Mueller and the Russia probe.
• "This was one of the biggest fears about Whitaker in law enforcement circles," a former senior DOJ official who used to work with Mueller told Business Insider.
• "His appointment not only endangers the status of the Russia investigation itself, but it could have an effect on the cooperation of those who have already pleaded guilty and others who Bob Mueller may be working to flip," this person said.

Cooperation talks between the special counsel Robert Mueller and Paul Manafort, the former chairman of President Donald Trump, have broken down in recent days, ABC News reported this week.

Manafort struck a plea deal with Mueller's team in September, shortly after he was convicted of eight counts related to tax fraud, bank fraud, and failure to report foreign bank accounts. Before his second trial, Manafort pleaded guilty to conspiracy and obstruction and agreed to cooperate with Mueller.

Since then, Manafort has met with prosecutors nearly a dozen times, and although Mueller's team has been asking the former Trump campaign chairman about a wide range of topics, they're "not getting what they want," the report said, citing one source with knowledge of the discussions.

Andrew Weissmann, a prosecutor working for Mueller, told US District Judge Amy Berman Jackson when Manafort's plea deal was announced that he would cooperate "in any and all matters as to which the government deems the cooperation relevant," including "testifying fully, completely" before a grand jury.

His plea agreement also states that if he "has failed to cooperate fully, has intentionally given false, misleading or incomplete information or testimony ... the defendant will not be released from his pleas of guilty but the Government will be released from its obligations..."

Read more: Robert Mueller has reportedly begun drafting his final report in the Russia probe

A source with direct knowledge of the matter told Business Insider that Manafort's plea deal with Mueller is still intact. But ABC News reported that the dispute between the two sides stems from suspicions that Manafort is not being entirely forthcoming about all the information he may know relevant to the Russia investigation.

The former Trump campaign chairman is a significant figure of interest in the inquiry, which is examining Russia's interference in the 2016 election, whether the Trump campaign colluded with Moscow, and whether Trump sought to obstruct justice after he learned of the investigation's existence last year.

As Manafort's cooperation stalls, Trump appoints a Mueller critic to oversee the Russia probe

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It's unclear why talks between Manafort and Mueller have reportedly stalled. Manafort's team initially mounted an aggressive defense against Mueller, reportedly in the hopes that it might catch the president's attention and prompt him to come to Manafort's aid. But Manafort shifted gears and struck a plea deal after his first trial resulted in a conviction.

Meanwhile, the landscape of the FBI's Russia probe may be set to shift drastically in the coming months, thanks to Trump's decision to oust Attorney General Jeff Sessions earlier this week and replace him with the former US attorney Matthew Whitaker, who will serve as acting attorney general until the Senate confirms a permanent replacement.

Whitaker, who was once described as the West Wing's "eyes and ears" in the DOJ, has a long history of making controversial remarks about both Mueller and the Russia investigation.

Read more: 'Seriously? This guy?': Matthew Whitaker's appointment as acting attorney general has FBI and DOJ officials in a 'daze'

"This was one of the biggest fears about Whitaker in law enforcement circles," a former senior DOJ official who used to work with Mueller when he was FBI director told Business Insider. "His appointment not only endangers the status of the Russia investigation itself, but it could have an effect on the cooperation of those who have already pleaded guilty and others who Bob Mueller may be working to flip."

"It's hard to say whether that's what happened in Manafort's case without knowing more details," this person said, "but it's certainly a possibility. And that should set off some alarm bells."

Among other things, Whitaker wrote in a CNN op-ed last year that Mueller had overstepped his mandate by digging into the Trump Organization's finances; he claimed, without providing evidence, that there was "no collusion" between the Trump campaign and Russia; and audio recently resurfaced of Whitaker falsely accusing "the left" of being responsible for "sowing this theory that essentially Russia interfered with the US election," which he claimed had been disproven and did not impact the election.

While he was Sessions' chief of staff, Whitaker met with Trump in the Oval Office over a dozen times, the Washington Post reported. And whenever Trump complained about the ongoing Russia investigation Whitaker "often smiled knowingly and nodded in assent," the Post added.

Despite his history of antagonism toward the special counsel, Whitaker reportedly has no plans to recuse himself from overseeing the Russia probe.