California Rep. Adam Schiff said "it's a sober moment for the country," telling Linsey Davis on ABC News Live on Thursday that the dignity of the Oval Office "will be tarnished by the conduct of the former president by his being charged criminally."

"I think you have to be guided by the facts and the law, and you have to set aside the political calendar and do what the law requires," said Schiff, a leading Democrat in the House. "I think that's the obligation of a district attorney, and I think that was done here. How this cuts politically, I really don't know. That, to me, is very secondary."

-ABC News' Imtiyaz Delawala and Anna Katharine Ping

Demonstrators gathered outside Manhattan Criminal Court and near Donald Trump's Mar-a-Lago estate in Florida in the wake of the indictment Thursday evening.

In Manhattan, a giant sign that stated "Trump lies all the time" could be seen unfurled outside Manhattan Criminal Court, where police had erected barricades last week ahead of a possible indictment.

Meanwhile, several supporters gathered near Mar-a-Lago with Trump 2024 flags and signs.

Senate Majority Leader Chuck Schumer urged "Trump’s critics and supporters to let the process proceed peacefully and according to the law" in a statement following the indictment of the former president.

"Mr. Trump is subject to the same laws as every American," Schumer said. "He will be able to avail himself of the legal system and a jury, not politics, to determine his fate according to the facts and the law."

Lawmakers on both sides of the aisle took to Twitter to react to the historic indictment on Thursday evening, laying bare the sharp partisan divide when it comes to Donald Trump.

GOP House and Senate members decried the investigation by the Manhattan district attorney as a political prosecution.

Many Democrats, on the other hand, praised the decision as proof "no one is above the law."

Read more here.

-ABC News' Alexandra Hutzler

Stormy Daniels' lawyer, Clark Brewster, issued a statement on the indictment, saying: "The indictment of Donald Trump is no cause for joy. The hard work and conscientiousness of the grand jurors must be respected. Now let truth and justice prevail. No one is above the law."

While the indictment remains under seal, Trump had been under investigation by the Manhattan district attorney over a $130,000 payment he made to the adult film actress to keep her from going public with a claim of an affair, which he denies.