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!"

After Michael Cohen implicated Trump in the hush money scheme in August 2018, Trump was "furious," prosecutor Josh Steinglass told the jury.

"His fixer had done the unthinkable, and Trump immediately went on the attack -- an attack that continues to this day," he said.

Steinglass showed a tweet Trump posted the following day: "If anyone is looking for a good lawyer, I would strongly suggest that you don't retain the services of Michael Cohen!"

"This is the day after he pled guilty," Steinglass said.

Steinglass argued that Trump's tweets after Cohen pleaded guilty in 2018 were warning messages to other potential witnesses who could cooperate against him.

"These tweets were not only designed to punish Cohen," Steinglass said. "Cooperate or you will face the wrath of Donald Trump," was the message they conveyed.

Steinglass described a "vexatious and punitive lawsuit" Trump filed against Michael Cohen and a defamation suit against Stormy Daniels as evidence of his punitive means against people who epoks out against him.

After a series of sustained objections regarding Trump's tweets and their alleged impact on Cohen's safety, Judge Merchan smiled and told the jury, "This might be a good time to take our last recess of the day."