After attorneys for each side introduced themselves, Judge Juan Merchan said that before jury selection can begin "there are a couple of loose ends we need to go over before we start."

The first item, Merchan said, was a pair of motions filed by Trump's legal team seeking his recusal from the case, citing his past comments in interviews and his daughter's work with a Democrat-affiliated firm.

The motions, Merchan said, cite "pages and pages of screen grabs, articles, social media posts and the like" that amount only to "a series of inferences, innuendos, and unsupported speculation."

To call them "attenuated is an understatement," Merchan said.

Merchan denied the motion and said the court would not address the matter further.

"All rise," the bailiff announced at 9:59 a.m. ET. "This is the People of the State of New York v. Donald J. Trump."

And with that, proceedings are underway.

Members of the prosecution and the defense, including the former president, stood briefly as Judge Juan Merchan entered the courtroom and took his seat on the bench.

Manhattan District Attorney Alvin Bragg entered the courtroom shortly before court went into session.

Former President Trump arrived at the courtroom at 9:32 a.m. flanked by members of his legal team.

In brief remarks to reporters on the way in, he called his criminal trial an "assault on America."

"Nothing like this has ever happened before," Trump said, marking his first comments of the day as he becomes the first former American president to face criminal charges.

"There is no case," he said. "This is political persecution."

Trump also attacked President Joe Biden and said the case should not go forward.

Upon entering the courtroom, he sat at the defendant's table as his lawyers and court officers buzzed around him.

Several members of the Manhattan district attorney’s office have arrived in the courtroom.

Proceedings are scheduled to begin at 9:30 a.m. ET.

The U.S. Secret Service has held meetings and started planning for what to do if former President Trump were to be held in contempt and Judge Juan Merchan opted to send him to short-term confinement, officials familiar with the situation tell ABC News.

Prosecutors said at this point they are seeking a fine.

"We are not yet seeking an incarceratory penalty," assistant district attorney Chris Conroy said, "But the defendant seems to be angling for that."

Officials do not necessarily believe Merchan would put Trump in a holding cell in the courthouse but they are planning for contingencies, the officials said.

There have be no discussion about what to do if Trump is convicted and sentenced to prison, they said.

"Under federal law, the United States Secret Service must provide protection for current government leaders, former Presidents and First Ladies, visiting heads of state and other individuals designated by the President of the United States," the Secret Service said in an official statement. "For all settings around the world, we study locations and develop comprehensive and layered protective models that incorporate state of the art technology, protective intelligence and advanced security tactics to safeguard our protectees. Beyond that, we do not comment on specific protective operations."

-Josh Margolin and Luke Barr