But given Manafort's pre-existing financial connections to Russia, his agreement to help prosecutors with further investigations will most certainly feed speculation and theories that there's more to these relationships than we're now publicly aware of, beyond what we've been told about Russian lobbyists offering stolen emails and data from Hillary Clinton's campaign to Trump's team.
But Friday's announcement was a political blow to the presidency ahead of 6 November mid-term elections that could determine whether or not Republicans maintain control of Congress.
His decision to plead guilty, indicated in a court filing on Friday, came just days before jury selection was set to begin September 17 in Washington, where Mueller accused him of conspiring to launder money, acting as an unregistered foreign agent of Ukraine and obstructing justice. Manafort is the fifth person linked to Trump to plead guilty to criminal charges.
White House press secretary Sarah Sanders said the Manafort case has nothing to do with Trump.
The White House says Manafort's decision to plead guilty and cooperate with Mueller is "totally unrelated" to President Donald Trump.
In late July, an attorney for Manafort told CBS News' Paula Reid that there was "no chance" his client would cooperate with the special counsel in its Russian Federation probe.
In brief responses, Manafort, 69, said he had sufficient time to consider his plea and that he was of sound mind.
With a plea deal, Manafort would avoid a trial that was set to last at least three weeks and posed the potential of adding years onto the 7 to 10 years he is already facing from his conviction in Virginia last month.
A guilty plea helps Manafort avoid the possibility of additional prison time in the event that the Washington jury were to have convicted him. "People aren't going to say they will run against Trump unless they have the infrastructure but I've been trying to persuade people that it may not be that hard", he added.
In August, Manafort was convicted at trial in Alexandria, Virginia, on charges that pre-dated his stint on Mr Trump's campaign and involved his work with pro-Russian politicians in Ukraine. In Virginia, he was found guilty on five tax fraud charges, one charge of hiding a foreign bank account, and two bank fraud charges - all felonies.
The special counsel's office issued the following statement regarding the plea: "Court has scheduled an arraignment and plea agreement hearing today for US v. Paul J. Manafort, Jr., 69, of Alexandria, Va., at 11 a.m".
Judge Amy Berman Jackson said in court Friday that Manafort must participate in interviews and debriefings, provide documents and testify in future cases.
Manafort refused for months to assist Mueller's inquiry before admitting guilt to criminal charges that he concealed money from tax authorities.
Prosecutor Andrew Weissman said in court Friday that Manafort had struck a "cooperation agreement".
Manafort is expected to appear in a USA district courtroom in Washington, D.C., later Friday morning. Given that Manafort and Trump have enjoyed an association, in one form or another, since the 1980s, it seems most improbable. The crimes Manafort has been convicted of are not directly connected to Trump and his campaign in any way and a lot of them preceded Manafort's work for Trump.
Manafort was in attendance at the now-infamous June 9, 2016, Trump Tower meeting between himself, Trump's son Donald Trump, Jr., son-in-law Jared Kushner, and a group of Russians led by a Kremlin-linked lawyer, as Inquisitr has covered.
The investigation has exposed the inner workings of the Russian influence campaign against American elections, a detailed and elaborate scheme by Manafort and Gates to hide money made through foreign lobbying work from the USA government and multiple instances of people later lying to investigators about their behavior. Trump's critics have pointed to the meeting as evidence of the collusion with Russian Federation that Trump denies.
Because it's Friday, that means we're getting a massive news dump. During the convention, the party's platform on Ukraine was altered in a way that made it more in line with Russian interests. A fully co-operative Manafort can end the mystery.
Manafort served for several months on the campaign, including as campaign chairman, until he was sacked in August 2016, amid revelations of the scope of his consulting and lobbying work for Ukrainian politicians, including then-President Viktor Yanukovych.
"As always, Rule No. 1 with Mueller, you don't know what he knows", Litman said.