Newark, New Jersey - New Jersey mistakenly registered roughly 6,600 non-US citizens to vote ahead of the 2024 election, the governor said Tuesday, while rejecting President Donald Trump's renewed push for nationwide voting restrictions.

Governor Mikie Sherrill, a Democrat, said fewer than 400 of those registered due to the "serious software error" had voted, and that the registrations were across party lines.

"I am appalled by the reckless failures that allowed this to happen and the lack of transparency shown by those in charge at the time," Sherrill said in a statement.

The incident occurred between June 2023 and June 2024, during the term of Sherrill's Democratic predecessor, Phil Murphy.

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The revelation comes after Republican Trump, who has never accepted his 2020 election defeat, revived unsupported allegations of mass voter fraud ahead of the November midterms that many expect him to dispute.

The president claimed in a televised address last week that more than 250,000 non-US citizens were registered to vote in four states, including New Jersey, as he urged lawmakers to adopt his SAVE America Act.

The bill would require proof of US citizenship to register to vote as well as photo identification at polling places, while also imposing new limits on mail-in ballots.

"As the Trump Administration tries to weaponize elections for political gain, I am ensuring we protect our elections. Let me be clear: Donald Trump has zero credibility on the issue of election integrity," Sherrill said.

"The difference is simple: when we find a problem, we don't hide it, deny it, or invent conspiracies. We investigate it, we fix it, and we tell the public."

Sherrill said the error meant around 6,600 people who indicated they were not US citizens when applying for drivers' licenses and ID cards between June 2023 and June 2024 were registered anyway. She added that she has ordered their removal from the voter rolls and sought an investigation into the incident.

On Monday, a New Jersey judge denied a lawsuit by the Republican National Committee seeking access to the state's voter rolls.

Trump's claim that the 2020 election was "rigged" has never been substantiated. More than 60 lawsuits produced no ruling establishing fraud capable of changing the outcome, while recounts, audits, and his own Justice Department found none.