Donald Trump's motorcade has arrived at the New York State Supreme Courthouse in lower Manhattan.

Court is scheduled to get underway at 10 a.m. ET, with Trump scheduled as the day's only witness.

Donald Trump, in New York, had a prep session with his lawyers Sunday ahead his testimony, sources tell ABC News.

Trump's mood during the session fluctuated between fits of anger regarding the case and being "in a good head space," according to sources.

The former president "can be a good witness if he stays focused," one source said.

Former President Trump is due in court to begin his testimony in his $250 million civil fraud trial at 10 a.m. ET.

Hundreds of members of the news media are huddled outside the New York State Supreme Courthouse ahead of Trump's arrival, with some having waited overnight.

After multiple in-court disputes about communications between him and his law clerk, Judge Arthur Engoron modified his limited gag order to cover attorneys in former President Donald Trump's civil fraud trial.

"Defendants may reference my staff as is appropriate to ask about scheduling issues or the management of the trial, which is an integral part of their jobs. What they may not do is to make any further statements about internal and confidential communications (be it conversations, note passing, or anything similar) between me and my staff," Engoron wrote in his supplemental limited gag order on Friday.

Engoron wrote that defense lawyers Chris Kise, Alina Habba, and Clifford Robert made "repeated, inappropriate remarks about my Principal Law Clerk, falsely accusing her of bias against them and of improperly influencing the ongoing bench trial."

The attorneys have raised multiple arguments during the trial that Engoron and his clerk passing notes between each other suggests impropriety and is distracting. Going forward, if the lawyers want to object to communications with his clerk, Engoron advised that they refer to the order as a "blanket statement."

"This gag order is as narrowly tailored as possible to accomplish its purpose, which is to protect the safety of my staff and promote the orderly progression of this trial," Engoron said.

To justify the safety threat, Engoron added that his chambers has received "hundreds of harassing and threatening phone calls, voicemails, emails, letters, and packages" since the start of the trial,

The judge threatened "serious sanctions" for violations of the extended order.

Former president Donald Trump and his company bid $1 billion in 2014 in an attempt to purchase the Buffalo Bills football team.

The only problem was that Trump needed a bank to help finance his bid.

Former Deutsche Bank executive Nicholas Haigh testified that when Trump turned to his bank for help, bank executives declined, fearing it would increase their financial exposure to Trump.

"Deutsche Bank was not willing to increase its credit exposure to Donald Trump at that time," Haigh said.

But the bank was still willing to help Trump by sending a letter to support his bid, according to Haigh -- on the condition that Trump Organization controller Jeffrey McConney certify that the company was still in compliance with the covenants of the three outstanding loans the bank had given Trump.

McConney verified that Trump had over $300 million in liquid assets in 2014, and that it suffered no material decrease in the value of his illiquid assets, according to a document entered into evidence today.

With that verification, Deutsche Bank issued a letter that Trump had the "financial wherewithal" to fund his bid.

Trump's effort to purchase the Bills was ultimately unsuccessful.