The courtroom in the Manhattan Criminal Courthouse is packed with reporters and security ahead of Michael Cohen's testimony.

Approximately 70 reporters are crammed into the gallery of the courtroom, seated on wooden benches that seat six per row. Five members of the public are seated in the back of the gallery behind the prosecution counsel table and jury box, and five court officers are scattered throughout the courtroom.

On the right side of the courtroom, earlier witnesses Jaden Jarmel-Schneider and Georgia Longstreet are seated near computer monitors. Both work as paralegals for the Manhattan district attorney's office and testified as part of the prosecution's case.

Jarmel-Schneider introduced phone records and a summary exhibit about the falsified documents into evidence, while Longstreet introduced Trump's social media posts into evidence.

Several members of the public waited overnight to secure a spot in the courtroom for Michael Cohen's testimony, traveling from as far as Los Angeles for the momentous day in court.

Michael Powers told ABC News that he joined the line at 2:30 p.m. yesterday to secure his spot in court, though he enlisted the help of professional line sitters to hold the spot overnight. He rejoined the line at 5:00 a.m.

"It's history in the making," Powers said. "This isn't gonna happen very often."

Powers said he prioritized seeing Michael Cohen's testimony due to its importance to the prosecution's case.

"I find him credible" Powers said. "He's lied in the past, but he lied for Donald Trump in my opinion, so I think he'll be a good witness."

Other members of the public waited overnight without the use of line sitters, including Chris Sagastizabal, who joined the line at 6:45 p.m. on Sunday with two friends.

"I changed my work schedule," Sagastizabal said.

Five members in the public have been seated in the courtroom this morning, with several others seated in a nearby overflow room.

Michael Cohen has arrived at the lower Manhattan courthouse ahead of today's expected testimony.

He did not speak to reporters on his way in.

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

Michael Cohen, who for nearly a decade was Donald Trump's trusted adviser, personal attorney, and self-described "attack dog with a law license," is scheduled to take the stand this morning as the prosecution's star witness in Trump's criminal hush money trial.

According to prosecutors, Cohen was in the room in when Trump and former National Enquirer publisher David Pecker agreed to a catch-and-kill scheme to hide negative information about Trump from 2016 voters, and Cohen himself made a $130,000 payment to Stormy Daniels to buy her silence about an alleged 2006 sexual encounter with Trump. The former president, who has denied the encounter took place, is on trial for allegedly falsifying business records related to his company's reimbursement to Cohen in 2017.

But Cohen's value to the prosecution's case could be endangered by the disbarred lawyer's credibility issues. Cohen pleaded guilty in 2018 to tax evasion, campaign finance allegations, and lying to Congress in what Cohen says was an effort to protect Trump. The former president's lawyers have also argued that Cohen perjured himself again when he testified at Trump's civil fraud trial last year, and accuse Cohen of making his livelihood off books and podcasts that antagonize Trump.

Cohen is the final key witness in the prosecution's case, after which the defense will present its case.

Jurors saw an April 21, 2018, email where Michael Cohen's attorney at the time, Robert Costello, told Cohen, "Sleep well tonight, you have friends in high places."

"The friend in high places was President Trump," Cohen testified.

"It let me know that I was still important to the team, and stay the course, that the president had my back," Cohen said about Costello's emails.

Jurors then saw another email from Costello dated June 13, 2018.

"Since you jumped off the phone rather abruptly, I did not get a chance to tell you that my friend has communicated to me that he is meeting with his client this evening and he added that if there was anything you wanted to convey, you should tell me and my friend will bring it up for discussion this evening," Costello wrote.

According to Cohen, the aforementioned client was Donald Trump.

Asked about the vagueness of the email, Cohen testified that it was "sort of to be covert -- it is all back channel. Sort of eye spy-ish. Didn't want to put anybody's name."

Jurors then saw a June 2018 email between Cohen and Costello that suggested their relationship had begun to fray.

"I must tell you quite frankly that I am not used to listening to abuse like today's conversation," Costello wrote, referencing an "unfortunate outburst" by Cohen.

"Please remember if you want or need to communicate something, please let me know and I will see that it gets done. I hope I am not wrong but it seems to both Jeff and I that perhaps we have been played here," Costello wrote, referencing the back channel to Trump.

Cohen told the jury he was concerned about his communications with Costello making their way to Trump, and he began looking for other lawyers.

Cohen said Costello was "again pressuring me as he had done with constant calls and sending me emails and so on. He wanted to absolutely be retained to represent me in this matter. He was angered that I was willing to sit down with another attorney but not sit down with them, so I had enough."