WASHINGTON (TNS) — President Donald Trump unleashed a flurry of messages attacking Hillary Clinton and Democrats, a day before the first charges may be announced from a special prosecutor investigating Russian involvement in last year's election.

"There is so much GUILT by Democrats/Clinton, and now the facts are pouring out. DO SOMETHING!" Trump posted on Twitter.

"The Dems are using this terrible (and bad for our country) Witch Hunt for evil politics," he wrote, adding that Republicans are "are now fighting back like never before."

Minutes before the president's Twitter account came alive, former U.S. attorney Preet Bharara said on CNN's "State of the Union" that people should watch Trump's reaction to any charges that might emerge in the investigation being led by special counsel and former FBI Director Robert Mueller.

"I would look for a couple of things. One, whether or not Donald Trump has some reaction and talks in a way that could be used against him in the future, because Bob Mueller would do that," Bharara said.

"The second thing I would look at is to see if the president of the United States is sending some kind of message to the potential defendant or other witnesses," he said. Whether the president plans to pardon people facing charges should be watched "very, very closely," Bharara said.

A grand jury has approved the first charges stemming from the investigation into Russian meddling in the 2016 election and possible collusion with Trump's campaign, according to multiple reports.

The charges are sealed under orders from a federal judge and the identity of a person or persons facing charges hasn't been revealed.

Rep. Adam Schiff of California, the top Democrat on the House Intelligence Committee, said on ABC's "This Week" that lawmakers "haven't been informed" of who may be charged Monday, and that it wouldn't be appropriate for Mueller to say.

Rhetoric on all sides has been stepped up, with the Wall Street Journal last week calling on Mueller to step down. New Jersey Gov. Chris Christie, a Republican who has advised Trump, stopped short Sunday of demanding a resignation, but signaled that the prosecutor is being closely watched.

"He has to be very, very careful about making sure that the public believes that he has no conflicts and that his integrity is unquestioned," Christie said on CNN. The president isn't under investigation, Christie said.

Christie and Schiff downplayed Trump's ability to pardon defendants before a criminal case is completed, as he did for former Phoenix-area Sheriff Joe Arpaio Aug. 25. While Schiff called Trump's pardon of Arpaio "a horrible precedent," he said the president's power is not unlimited and can't be used to obstruct justice.

(Ben Brody and Mark Niquette contributed to this report.)