Washington (AFP) - The New York hush money case against Donald Trump was considered the weakest by many legal experts but it resulted in a stunning conviction and is likely to be the only one of the four facing the ex-president to be tried before the November election.

Trump, 77, has been indicted in Washington and Georgia on far more serious charges -- seeking to overturn his 2020 election loss to Democrat Joe Biden.

The Republican, who is seeking to recapture the White House in November, also faces charges in Florida for allegedly hoarding top secret documents after leaving office in January 2021 and refusing to return them.

Rick Hasen, a law professor at the University of California, Los Angeles, said the New York case, in which Trump was convicted of falsifying business records to cover up a payment to a porn star, was "relatively minor."

"Trump should have faced trial for trying to subvert the 2020 election," Hasen said on X, formerly Twitter. "That hasn't happened and likely won't."

Randall Eliason, a former federal prosecutor, said the New York hush money case was a much simpler case than the others, focused on "private conduct" by Trump before he became president.

"That allowed it to proceed more quickly because it didn't involve a lot of difficult constitutional questions," Eliason told AFP.

The other three cases facing Trump are considerably more complicated because they involve actions taken while he was president or after leaving the White House.

Trump had been set to go on trial in Washington on March 4 on the election subversion charges but the case has been frozen pending a Supreme Court ruling on his claim that a former president is immune from prosecution.

The conservative-dominated Supreme Court heard arguments on the immunity question at the end of April.

A ruling is expected by the end of June but it is unlikely a trial can take place before November, when Trump is expected to take on Biden in a rematch of their 2020 contest.

Trump is charged in Washington with conspiracy to defraud the United States, obstructing the January 6, 2021 joint session of Congress held to certify Biden's victory and conspiring to deny Americans the right to vote.

'Massive case'

The other election interference case -- in Georgia -- has been bogged down in appeals and a bid by Trump and his co-defendants to disqualify district attorney Fani Willis following revelations she had a romantic relationship with the man she hired as a special prosecutor.

Evidence in the Georgia case includes a taped phone call in which Trump asked a top state election official to "find" enough votes to reverse the result.

Eighteen co-defendants were indicted along with Trump on racketeering and other charges, including his former personal lawyer Rudy Giuliani and White House chief of staff Mark Meadows.

"It's just a massive case," Eliason said. "It's going to take a long time."

In Florida, Trump is accused of endangering national security by holding onto secret nuclear and defense documents after leaving the White House.

Trump allegedly kept the files -- which included records from the Pentagon and CIA -- unsecured at his Mar-a-Lago home in Florida and thwarted efforts to retrieve them.

The case had been scheduled to go on trial on May 20 but has been postponed indefinitely by District Judge Aileen Cannon, a Trump appointee.

Trump's lawyers have sought repeatedly to delay his various court cases until after the November vote, when he could potentially have the federal charges against him dropped if he wins.

He would not be able to pardon himself in the New York case, however, as it was brought not by the federal government but by the state and only the governor could clear his name.