By Andrea Shalal and Nandita Bose
GREENWICH, Connecticut (Reuters) -President Joe Biden on Monday for the first time called former President Donald Trump a "convicted felon" who poses a higher threat to the United States if he wins another term - the most biting attack on his opponent's legal troubles to date.
Trump became the first U.S. president to be convicted of a crime last week when a New York jury found him guilty of falsifying documents to cover up a payment to silence a porn star ahead of the 2016 election.
"For the first time in American history, a former president that is a convicted felon is now seeking the office of the presidency," Biden told a small group of donors during a fundraiser in Greenwich, Connecticut.
"But as disturbing as that is, more damaging is the all-out assault Donald Trump is making on the American system of justice," Biden said, adding it was "reckless and dangerous" to say the justice system is rigged because Trump and his allies don't like the outcome.
Biden until now had largely stayed away from addressing Trump's guilty verdict to avoid creating the impression he was politicizing the process, according to Biden campaign officials.
The president's comments on Monday offer a glimpse into how he and his campaign could use Trump's conviction to make the case to voters Trump is unfit for office - an issue that could help define this year's presidential race by pushing Trump's felonies to the center of the election.
A Trump campaign spokeswoman said on Fox News its "shameful" for the Biden campaign to call Trump a convicted felon. Trump has railed against the verdict and the legal proceedings since he was convicted, and plans to appeal. On Sunday, he said he would accept home confinement or jail time but that it would be tough for the public to accept.
Earlier in the day, Biden's son Hunter was in court for a criminal case against him over his purchase and possession of a revolver in 2018, a historic criminal prosecution of a sitting president's son with the potential to influence the 2024 presidential election.
Biden did not comment on his son's legal troubles. He had issued a statement earlier in the day saying "Jill and I love our son and we are so proud of the man he is today," and added that a lot of families have loved ones who have overcome addiction.
At the Greenwich fundraiser, Biden also called Trump "unhinged" and unable to accept defeat. He stressed Trump's earlier comments about terminating the U.S. Constitution and wanting to be a dictator on day one if he wins a second term.
"Throughout this campaign Trump has made it clear he is running to exact for revenge. Now after his criminal convictions it's clear he's worried about preserving his freedoms," Biden said.
Democrats are wrestling with how central Trump's felonies should be to Biden's reelection campaign. Many - including top officials in Biden's campaign - are taking a wait-and-see approach to advertising and new strategies and want to see polls and voter feedback before they react strongly to this unprecedented moment in U.S. history.
A Reuters/Ipsos poll last week found 10% of Republican voters said they are less likely to vote for Trump in November after his conviction.
Trump still faces criminal charges in three other cases: a Georgia election interference case, a Florida documents case and a federal election interference case. He is also appealing the results of his civil trials.