A United States appeals court has declined to allow the administration of President Donald Trump to implement controversial new rules about how mail-in voting is conducted, with less than eight weeks left before the November 3 midterm elections.

On Thursday, the First Circuit Court of Appeals in Boston, Massachusetts, decided against lifting an injunction against the rules, issued by a lower court last week.

The US Supreme Court is currently weighing a similar request.

At issue are a set of finalised rules released by the US Postal Service (USPS) in late August that would place new requirements on mail-in balloting.

The rules direct states to redesign mail-in ballots to include unique barcodes that can be scanned, so that the federal government may track them.

States would also be required to submit a list of voters slated to receive ballots by mail. The Postal Service would retain the right to “not transmit mail-in or absentee ballots” if the mail-outs do not comply with the new standards or if the voters in question do not appear on the submitted lists.

The case heard on Thursday involved a coalition of voting rights advocacy groups, including the League of Women Voters.

They argued that the new rules, championed by Trump, a Republican, would effectively disenfranchise certain voters who rely on mail-in ballots.

But the Trump administration has argued that the rules are necessary to ensure election security.

In asking the appeals court to lift the injunction, the ‌US Department of Justice argued that the plaintiffs’ case appeared to be based on an unfounded premise that Postal Service intends to seize control of election administration.

It emphasised that state election officials ‌would ‌retain full control over who is permitted to vote by mail and that the Postal Service’s role would be limited to ensuring that envelopes for the mail-in ballots comply with the “modest” new design requirements.

The appeals court, however, denied the Trump administration’s motion to dismiss the injunction, citing the potential for confusion ahead of the midterm vote.

It also affirmed parts of the lower-court ruling, issued by US District Judge Indira Talwani, an appointee of Democratic President Barack ⁠Obama.

“The district court made detailed findings about the chaos and widespread disenfranchisement that would occur between now and November 3 should the Final Rule take immediate effect,” the appeals court said in Thursday’s decision.

It cited issues including that “it would be impossible for some States to reprint compliant envelopes” and that the Postal Service would face the “herculean task” of scanning “tens of millions of ballot envelopes” using a digital portal that is not yet functional.

“There is no countervailing record evidence disputing the district court’s findings on these points,” the appeals court added.

Under the US Constitution, election administration falls to the states. But Trump has pushed for greater voting restrictions ahead of the pivotal midterms, in an effort to combat alleged election fraud.

Critics, however, have framed his actions as an effort to sway the outcome. Currently, Trump’s Republican Party holds majorities in both chambers of Congress. But with Trump facing drooping poll numbers, Democrats are seeking to flip Congress to their control.

All 50 US states allow ⁠for some form of mail-in voting. Twenty-nine states allow voters to ask to cast ballots by mail without providing a reason, and eight conduct their elections entirely ⁠by mail.

The legal battle over the mail-in ballots has stretched on for weeks, creating uncertainty ahead of the vote.

In addition to the voting advocacy groups challenging the new rules, a group of 24 states, plus the District of Columbia, have also filed a lawsuit.

Last month, the US Supreme Court lifted an earlier injunction issued by Judge Talwani blocking the rules from taking effect.

The Trump administration last week once again made an emergency petition to the high court to intervene and pause Talwani’s ruling.

The new rules came after Trump issued an executive order in March calling for tighter rules to govern voting by mail.

Trump has also repeatedly pushed the false claim that his defeat in the 2020 presidential election was the result of widespread voter fraud.

An anonymous whistleblower statement released ⁠on September 1 by Democratic Senator Richard Blumenthal alleged that the Postal Service had rushed to implement the new rules, but that the result was a faulty system that risks disrupting the delivery of mail-in ballots.