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.

Donald Trump being formally accused of a crime could change the outlook for the still-forming field of Republican presidential candidates in 2024 -- either rallying primary voters primed by his talk of the "deep state" and "retribution" or opening up an unprecedented line of criticism for Trump's rivals.

The indictment itself isn't disqualifying, legally speaking. The U.S. Constitution doesn't prevent people under indictment or criminal investigation from running for the White House, experts have told ABC News, so the former president could still be reelected despite the indictment -- and would still be eligible even if it leads to a conviction, regardless of practical obstacles like potential incarceration.

ABC News has learned that former president Donald Trump has been indicted, according to multiple sources with knowledge. The charges were not immediately clear.

Manhattan District Attorney Alvin Bragg has notified Trump.

Trump's former attorney, Michael Cohen, said in a statement, "I do take solace in validating the adage that no one is above the law; not even a former President."

"Today’s indictment is not the end of this chapter; but rather, just the beginning," Cohen said. "Accountability matters and I stand by my testimony and the evidence I have provided to [the district attorney's office]."

The Manhattan grand jury weighing charges against former President Donald Trump will not convene on Wednesday and is expected to meet Thursday on other matters, sources familiar with the situation told ABC News.

The proceeding is conducted in secret and the grand jury could be presented with evidence or vote at any time.

Sources familiar with the matter told ABC News the Manhattan district attorney’s office is also investigating a $150,000 payment to Playboy model Karen McDougal, who, like Stormy Daniels, claimed to have had an affair with Donald Trump.

The former president has denied having an affair with either woman and has called the investigation a witch hunt.

McDougal was paid for the rights to her story in August 2016 by American Media, publisher of the National Enquirer, which did not publish it, a practice known as catch and kill.

Michael Cohen, Trump’s former lawyer and fixer, has said he recorded Trump discussing reimbursement to American Media for the payment to McDougal, but the payment was never made.

Trump has not responded to ABC News' request for comment but in a 2018 interview with Fox News, he claimed he wasn't aware of any payment made to AMI to facilitate the alleged hush agreement.