Former President Donald Trump is expected to travel to New York on Monday, sources familiar with the matter told ABC News.

He is expected to appear in court on Tuesday at the earliest, the sources said, on what is expected to be around two dozen counts - including felonies.

The exact charges are unknown since the indictment will not be unsealed until Trump appears in court.

-ABC News’ Aaron Katersky, Katherine Faulders, John Santucci

As legal experts speculate on what charges lay inside the sealed indictment ahead of former President Donald Trump's expected surrender on Tuesday afternoon, many predict that prosecutors could try out a new legal theory to justify bringing the charges.

"This could be a novel legal theory," said Kate Shaw, a law professor at Cardozo and ABC News contributor, speculating on what charges the public could see against Trump while stressing it's unknown until the indictment is unsealed.

Read more here.

-ABC News' Libby Cathey

Former President Donald Trump has been charged with around two dozen counts, including felonies, sources familiar with the sealed indictment told ABC News.

The exact charges remain unknown since the indictment will not be unsealed until Trump appears in court on Tuesday.

The Manhattan district attorney’s office declined to comment.

The Senate sergeant at arms is warning of potential demonstration activity related to the indictment of former President Donald Trump.

"While law enforcement is not tracking any specific, credible threats against the Capitol or state offices, there is potential for demonstration activity," an email obtained by ABC News said.

Capitol Police "is working with law enforcement partners, so you may observe a greater law enforcement presence on Capitol Hill," the email said, adding that there could be "nationwide impacts to Senate state offices."

The Capitol Police declined to comment and the sergeant at arms didn't immediately respond to ABC News' request for comment.

-ABC News' Luke Barr

While 45% of Americans believe former President Donald Trump should face charges in an investigation by the Manhattan District Attorney's Office, 32% say he shouldn't have been indicted, according to a new ABC News/Ipsos poll.

Another 23% of American say they don't know whether the nation's 45th president should face charges.

While the charges have not been announced, a Manhattan grand jury that indicted Trump had been hearing evidence in a $130,000 hush money payment Trump allegedly made to adult film actress Stormy Daniels, who claims they had an affair. Trump has denied the allegations.

The poll showed a split in opinions along party lines. While 88% of Democrats said Trump should face charges, 62%, of Republicans said the former president should not have been charged while 16% said he should be charged, and the remainder was uncertain.

About 47% of Americans polled say the charges are politically motivated, echoing the sentiment from top GOP figures. About 79% of Republicans hold that view.

-ABC News' Brittany Shepherd