WASHINGTON: The Trump administration has intensified scrutiny of voter-registration records ahead of the Nov 3 midterm elections, using immigration databases, federal investigators and largescale data analysis to identify suspected non-citizens on voter rolls.

The campaign has brought Washington into conflict with 17 states, most recently California, where the Justice Department has sued over 20,000 people it identified as likely non-citizens registered to vote. The department wants the state to set aside their mail-in ballots until their citizenship can be verified.

Mail-in ballots are used more often by Democrats.

A Pew Research Center analysis of the 2024 election found that 44 per cent of Democratic voters voted by mail or absentee, compared with 26 per cent of Republican voters.

The dispute comes as both parties prepare for elections that will determine control of Congress, which shapes immigration policy, approves federal spending and oversees the administration. The outcome could have significant implications for President Donald Trump, whose immigration enforcement programme has become a defining feature of his presidency.

Internal documents obtained by the advocacy organisation Democracy Forward under the Freedom of Information Act shed light on the scale of the federal operation.

The166pages ofrecords show that Homeland Security Investigations (HSI), the investigative arm of Immigration and Customs Enforcement (ICE), obtained 48.4 million records from sources described as independent of the government.

The documents also show that investigators scrutinised voter-registration organisations and considered deploying undercover agents to investigate groups suspected of helping non-citizens register to vote.

The US Justice Department has warned state and local election officials they could face crimi-nal liability for knowingly counting ballots cast by ineligible voters.

Under the methodology outlined in a lawsuit against California, federal officials identify potential matches between voterregistration records and immigration-related information, then use federal records, including alien registration numbers, to assess citizenship status.

The process raises questions about the reliability of matching administrative records, particularly when immigrants may since have become naturalised US citizens. The dispute escalated on Oct 15, when the Justice Department sued California, alleging that more than 20,000 likely non-citizens were registered to vote.

The case has revived debate over federal and state authority in elections.

Federal law governs eligibility to vote in federal elections, while states administer elections and maintain voter-registration systems.

California challenged the federal approach, arguing that it needs reliable proof before taking action against voters whose eligibility remains unresolved.

Why immigrant voters matter? The investigation has particular political significance because naturalised citizens form a substantial electorate in many congressional districts. Of 46m immigrants living in the US, 24.5m are naturalised citizens eligible to vote, according to figures from the University of Virginia`s Weldon Cooper Center for Public Service.

An American Immigration Council analysis estimates that 22.5m eligible naturalised voters live across 284 congressional districts, including about 16m registered voters. In 126 districts, their estimated numbers exceeded the 2024 margin of victory.

Latino voters are an important part of this electorate. An NBC News! Telemundo poll published in October found that 59pc of Latino respondents favoured Democratic control of Congress, compared with 35pc who preferred Republican control. About two-thirds said Trump`s deportation policies had gone too far.