Republicans have latched on to the announcement after Trump’s lie-laden speech, but experts say DHS’s data is ‘designed to create a false argument’

Donald Trump and his allies quickly seized on an announcement from Mikie Sherrill, the New Jersey governor, on Tuesday that 6,600 noncitizens had registered to vote because of a software error, and fewer than 400 of them voted, using the disclosure to escalate false claims that there are scores of noncitizens on the voter rolls.

Trump seized on the news days after he said in a primetime speech that the Department of Homeland Security identified 278,000 noncitizens on the voter rolls in New Jersey and three other states. But a Guardian review of the letters the DHS sent the states shows the agency expressed less certainty about the number and has offered no explanation of its methodology.

Donald Trump delivered a primetime address to the country on Thursday, claiming that declassified intelligence showed Chinese interference in US elections. The US president revived long-running attacks on election security, despite a US intelligence assessment that found no evidence Beijing altered the 2020 vote, which he lost. The Guardian's voting rights reporter Sam Levine factchecks some of Trump's claims

• Trump is invoking foreign election interference to justify his own - Opinion