In short:

US President Donald Trump has criticised the Supreme Court for blocking his plan to restrict mail-in election ballots.

The regulation would have required states to provide voter-specific data and use agency-approved mail-ballot envelopes that would be tracked using barcodes.

What's next?

Attorney-General Todd Blanche says the administration is going to comply with the decision.

US President Donald Trump has criticised the Supreme Court after it rejected his push to restrict mail-in voting in the November midterm elections.

"This Supreme Court is bullied and cajoled by the Radical Left into making decisions that have set America back at least a hundred years," Mr Trump wrote on social media.

"These are not the people I interviewed to serve on the United States Supreme Court, they are merely a shell of their original selves," Trump continued on Truth Social, without naming any of the justices.

"It is a Court that will go down as having rendered some of the most destructive, hurtful, and damaging decisions in our Country's history."

Mr Trump appointed three justices — Neil Gorsuch, Brett Kavanaugh and Amy Coney Barrett — during his first term as president, building a 6-3 conservative majority and allowing the court to steer a dramatic rightward course since 2020.

On Monday, the court's decision preventing implementation of the rule, which the United States Postal Service (USPS) adopted at the president's direction, was brief and unsigned, as is typical when it handles emergency requests.

Mr Trump called it a "horrible, highly political, ruling".

Only conservative Justices Samuel Alito and Clarence Thomas publicly dissented.

Mr Trump referred to them as "legends, both".

US Attorney-General Todd Blanche told reporters later that the Trump administration would comply with the court's decision.

The ballots rule

The USPS regulation would have required states to provide voter-specific data and use agency-approved mail ballot envelopes that would be tracked using barcodes.

The USPS could then refuse to send out ballots that do not comply with the new standards or were associated with voters who did not appear on the lists.

Critics warned that the measure could disrupt the delivery of thousands of legitimate ballots as the November 3 vote approached and caused chaos, given imminent plans by many states to send out mail ballots to eligible voters.

The administration said the new rule would prevent voter fraud, though evidence of such fraud is rare.

Mr Trump's fellow Republicans are locked in a tight battle to retain control of Congress in the midterms.

Restricting mail-in ballots would stand to benefit Republicans given that Democratic voters disproportionately use mail-in ballots, according to various surveys.

Mr Trump signed his executive order targeting mail-in ballots in March after years of casting doubt on their security, though he often votes by mail himself.

Mr Trump has made false claims about widespread fraud in US elections, including his 2020 loss to former Democratic president Joe Biden.

"It is a big loss for Republicans, and America itself," Mr Trump wrote of the mail ballot ruling.

The Supreme Court has delivered several election-related rulings in recent months that have benefited Republicans, although last Thursday it blocked Missouri from using a redrawn congressional map favouring Republicans.

That was a setback to Mr Trump and his party's chances of maintaining its slim majority in the US House of Representatives in November's elections.

Reuters