The president claims the Russian Federation investigation, which has notched up a number of indictments and guilty pleas, including of some of those closest to him, is politically motivated.
"The Phony Witch Hunt continues, but Mueller and his gang of Angry Dems are only looking at one side, not the other". "Wait until it comes out how horribly & viciously they are treating people, ruining lives for them refusing to lie".
Cevallos said the special counsel likely had evidence to prove Manafort - or possibly even the president - lied to investigators.
Moments later, he continued his Twitter assault on the federal prosecutor.
"The Fake News Media builds Bob Mueller up as a Saint, when in actuality he is the exact opposite", Trump said in a series of tweets.
But with prosecutors saying he breached the agreement, Manafort now faces serious repercussions such as the possibility of prosecution on additional charges, including the 10 felony counts dropped when he made the deal.
Trump's attorney Rudy Giuliani has signaled that the White House will claim executive privilege to prevent Mueller's final report from public release, but Cevallos said the special counsel could reveal some of his strongest evidence at Manafort's sentencing.More news: Rakitic ruled out of Croatia's crucial clash with England at Wembley
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"Let these bad people go back to the Clinton Foundation and "Justice" Department", he fumed.
But Mueller's office says Manafort broke his promise and also broke federal law with "crimes and lies".
Monday's court filing did not go into detail about what exactly Manafort allegedly lied about, and the special counsel said it would submit a more detailed sentencing submission that "sets forth the nature of the defendant's crimes and lies, including those after signing the plea agreement" at a later date.
The charges were connected to his work in Ukraine for a Kremlin-connected politician.
The judge in DC District Court who received the update Monday night has not yet weighed in, and a sentencing for Manafort's guilty plea has not yet been scheduled.
The only reasonable explanation as to why Manafort would decide not to cooperate with Mueller, thus ensuring that his criminal sentence is much longer in length - perhaps one that amounts to a life sentence, given that Manafort is 69-years-old - is that he is now relying on a presidential pardon. He still faces a separate sentencing from a Virginia case where he was convicted of bank and tax fraud.
But the development also raised speculation that Manafort may be seeking to curry favor with Trump or protecting other associates who worked on the campaign.