Preet Bharara, former US Attorney for the southern district of NY, said Sunday that Trump's reaction to Monday's expected drama will be crucial.
A federal grand jury in Washington on Friday approved the first charges in the investigation led by special counsel Robert Mueller, according to sources briefed on the matter.
In July, the Federal Bureau of Investigation conducted an early morning raid on Manafort's northern Virginia home, and Mueller has since taken the unusual step of subpoenaing the former Trump campaign chairman's spokesman and former attorney.
The source did not disclose the name of the target or the nature of the charges. He sent three tweets but they did not refer to the reports.
Hannity - the Fox News host who played a key role in encouraging Trump's Republican supporters in Congress to announce this week that they're launching new investigations into Hillary Clinton - posted a cryptic tweet suggesting the news is somehow bad for Mueller, and another wondering why Clinton isn't being prosecuted.
A spokesman for Mueller declined to comment Friday night.
In a series of Twitter messages on Sunday morning, Trump did not comment on the news that the first charges resulting from Mueller's probe into presumed Russian interference in the election have been filed and tried to divert attention to the alleged actions by Clinton and other Democrats.
Reporters present saw a flurry of activity at the grand jury room, but officials made no announcements.
His widely-reported connections to corrupt former Ukrainian President Viktor Yanukovych sparked speculation he we used Russian agents to help Trump at the expense of Clinton.
The team also has shown interest in foreign lobbying conducted by former Trump campaign chairman Paul Manafort.
Manafort has become a central figure in Mueller's investigation, which has expanded to look at possible financial crimes by Trump campaign officials. The names that have popped up most often when discussing possible collusion with Russian Federation are Paul Manafort, Michel Flynn, and Carter Page.
According to the tweeting president, Clinton is personally responsible for the dossier that was initially financed by a conservative critic.