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

Trump's lawyer said on Sunday on ABC's "This Week" that he doesn't know what to expect when the former president is arraigned on Tuesday in New York City, given the historic nature of Trump's indictment.

"This is unprecedented. I don't know. I've done a million arraignments in that courthouse with celebrities and whatnot. But this is a whole different thing. We have Secret Service involved. I understand they're closing the courthouse for the afternoon. I just don't know what to expect to see," Joe Tacopina told "This Week" anchor George Stephanopoulos.

He likened the case to "persecution" and said the charges, which remain under seal, "revolved around" Trump paying money to adult film actress Stormy Daniels before the 2016 election to keep her from going public with a claim of an affair that Trump denies.

He told Stephanopoulos that he didn't know whether Trump would hold a press conference on Tuesday after he is arraigned.

"What I hope is that we get in and out of there as quickly as possible, that it's, at the end of the day, a typical arraignment," he said.

-ABC News' Tal Axelrod

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

A white powder was discovered in the mailroom at 80 Centre Street, where the Manhattan District Attorney has offices and where a grand jury has been meeting to hear evidence in former President Donald Trump's case, according to a court official. The powder was determined to be non-hazardous, officials said.

The powder came in an envelope addressed to "Alvin," an apparent reference to Manhattan District Attorney Alvin Bragg, according police sources.

Inside the envelope was a letter containing the typewritten message, “Alvin: I am going to kill you," with 13 exclamation points, according to sources.

This envelope followed a series of unfounded threats that targeted municipal offices in New York this week.

"For three days we got four emails," Susan Stetzer, district manager at Manhattan Community Board 3, told ABC News on Friday.

At least one of the messages prompted the court to pause a hearing in the New York Attorney General’s civil lawsuit against Trump.

None of the email messages mentioned Trump by name. One included what Stetzer described as a "horrible homophobic rant."

According to Stetzer, the messages came from @mail.ru domains and some contained Cyrillic characters. The FBI is aware but does not immediately assess that the emails came from Russia, according to a law enforcement official.

"We did not get one today so I’m hoping it stops," Stetzer said.

New York City courthouses will see increased security, the Office of Court Administration said Friday.