Steve Bannon, a former top adviser to Donald Trump, must report to prison by July 1 to serve a four-month sentence for contempt of Congress, a federal US judge says.

The decision means Bannon, who hosts a political podcast, will likely be behind bars for a critical stretch of the US presidential campaign as former president Trump faces Democratic President Joe Biden in the November 5 election.

The order by US District Judge Carl Nichols in Washington DC came after a federal appeals court last month rejected Bannon’s bid to overturn his conviction for spurning a subpoena from a congressional panel that investigated the January 6, 2021, attack on the US Capitol.

Outside the courthouse, Bannon said he would ask the US Supreme Court to intervene, casting his prosecution as politically motivated.

“I’ve got great lawyers, and we’re going to go all the way to the Supreme Court if we have to,” he said.

Bannon cast the case as politically motivated, saying “this is about shutting down the MAGA (Make America Great Again) movement”.

“There’s not a prison built or jail built that will ever shut me up,” he said.

Bannon was convicted in 2022 of two misdemeanour counts of contempt of Congress for refusing to turn over documents or testify to the Democratic-led House of Representatives committee.

He will be the second former top official from Trump’s White House to go to prison for refusing to co-operate with the committee.

Peter Navarro, a former trade adviser, is serving a four-month term.

Bannon was allowed to avoid serving the sentence during his appeal.

Prosecutors moved to end that reprieve after a three-judge panel of the US Court of Appeals for the District of Columbia Circuit rebuffed Bannon’s challenge to his conviction.

Bannon’s lawyers urged the judge to keep him free, arguing he can still appeal to the full DC Circuit court or the US Supreme Court.

Bannon has argued that he was advised by his lawyer that he did not have to comply with the subpoena and therefore did not intend to commit a crime.

But Nichols said after the appeals court’s ruling, there was no longer justification to keep Bannon free.

“I can no longer conclude that his appeal raises substantial questions of law” likely to overturn his conviction, the judge said.

Bannon, who no longer worked in the White House at the time, was part of a group of Trump advisers who sought to derail formal certification of Biden’s victory in the 2020 election.

The congressional panel said he may have had knowledge of events planned for January 6, 2021, when Trump supporters breached the Capitol in a failed bid to stop lawmakers from certifying the vote.

-AAP with AP