The prosecution's star witness, former Trump attorney Michael Cohen, called today's verdict "an important day for accountability and the rule of law."

"While it has been a difficult journey for me and my family, the truth always matters," he said.

Two senior Trump advisers who ABC News spoke with were extremely angry after the verdict.

Both said they were not surprised by the jury’s decision. One said, "The fix was always in," and the other added, "Not surprised -- it’s New York."

Donald Trump Jr., reacting to his father's guilty verdict, said, "The Democrats have succeeded in their yearslong attempt to turn America into a third-world s---hole. Nov. 5 is our last chance to save it."

The guilty verdict shows "no one is above the law," a representative for President Joe Biden's campaign said, adding, "But today's verdict does not change the fact that the American people face a simple reality. There is still only one way to keep Donald Trump out of the Oval Office: at the ballot box."

"Convicted felon or not, Trump will be the Republican nominee for president," Michael Tyler, communications director for the Biden-Harris campaign, said in a statement.

"A second Trump term means chaos, ripping away Americans' freedoms and fomenting political violence -- and the American people will reject it this November," Tyler said.

The White House offered a very brief comment, with a White House Counsel’s Office spokesperson saying, "We respect the rule of law, and have no additional comment."

Among the congressional response, Speaker of the House Mike Johnson, who traveled to Manhattan days ago to support Trump at the trial, said in a statement, "Today is a shameful day in American history. Democrats cheered as they convicted the leader of the opposing party on ridiculous charges, predicated on the testimony of a disbarred, convicted felon."

"President Trump will rightfully appeal this absurd verdict -- and he WILL WIN!" Johnson said.

Former President Donald Trump's campaign is already fundraising off of the guilty verdicts in his hush money trial, telling his supporters he has been convicted in a "rigged" trial.

"I was just convicted in a RIGGED political Witch Hunt trial: I DID NOTHING WRONG!" a fundraising email said. "They’ve raided my home, arrested me, took my mugshot, AND NOW THEY’VE JUST CONVICTED ME!" the email continues.

The email links to a fundraising page, in which Trump told his supporters, "I'm a political prisoner!"

Turning to Michael Cohen's testimony, the jury reheard his testimony, under questioning from prosecutors, that Pecker -- during the 2015 Trump Tower meeting -- vowed to keep an eye out for "anything negative about Mr. Trump" and flag them to Cohen.

Q: Could you tell the jury, please, what was discussed and what was agreed to at that meeting?

A: What was discussed was the power of the National Enquirer in terms of being located at the cash register of so many supermarkets and bodegas; that if we can place positive stories about Mr. Trump, that would be beneficial; that if we could place negative stories about some of the other candidates, that would also be beneficial.

Q: Was there anything else that Mr. Pecker said he could also do for Mr. Trump's candidacy?

A: Yeah.

Q: What, in substance, did he say?

A: What he said was that he could keep an eye out for anything negative about Mr. Trump, and that he would be able to help us to know in advance what was coming out and try to stop it from coming out.

Q: And who did he say he would get in touch with if his -- he was able to identify those types of stories?

A: The answer was: Me. Mr. Trump also. Knowing my relationship with David, "The two of you should work together. And anything negative that comes , you let Michael know, and we'll handle it."