Donald Trump allegedly offered to pardon Julian Assange if he claimed that Russia had nothing to do with a leak of Democratic party emails, according to arguments made as the Wikileaks founder prepares to block his extradition to the US.

The request to Mr Assange reportedly came from a former California Republican congressman and Trump ally, now thrust into the scandal at the heart of a federal investigation into foreign interference in US elections, lawyers for Mr Assange argue.

Former congressman Dana Rohrabacher, 72, did not immediately respond to a request for comment. The White House has denied the claims.

The leaked emails published by Wikileaks proved to be a campaign obstacle for Democrats and candidate Hillary Clinton.

Mr Assange faces decades in prison if found guilty on more than a dozen charges involving the release of classified documents obtained by former US Army intelligence officer Chelsea Manning.

Key moments for Julian Assange Show all 9 1 /9 Key moments for Julian Assange Key moments for Julian Assange The situation today Assange was arrested after Metropolitan Police officers were invited into the Ecuadorian embassy on April 11 2019. How did it come to this? Ruptly TV Key moments for Julian Assange The break Assange shows the front page of the Guardian on July 26 2010, the day that they broke the story of the thousands of military files leaked by WikiLeaks AFP/Getty Key moments for Julian Assange Wanted A warrant for Assange's arrest was issued in August 2010 for counts of rape and molestation in Sweden AFP/Getty Key moments for Julian Assange Ruling The UK's Supreme Court ruled in 2012 that Assange should be extradited to Sweden to face trial Getty Key moments for Julian Assange Sanctuary Following the ruling, Assange was given asylum by the Ecuadorian governement over fears that his human rights would be violated if he were extradited, he has since remained in the embassy in London Getty Key moments for Julian Assange A friend in Pam Friend Pamela Anderson delivers lunch to Assange at the embassy in October 2016. She has since spoken against his arrest Getty Key moments for Julian Assange Arbitrarily detained A UN panel found in 2016 that Assange had been arbitrarily detained and that he had not been able to claim his full right to asylum. It urged Sweden to withdraw the charges against him Getty Key moments for Julian Assange The cat ultimatum Last year, the Ecuadorian embassy threatened to revoke Assange's internet access unless he stopped making political statements online and started taking better care of James, his pet cat. Assange accused Ecuador of violating his rights Reuters Key moments for Julian Assange Arrest Assange was arrested on April 11 2019. Ecuador revoked his asylum status and invited the Metropolitan Police in to the embassy to arrest him. Reuters

Mr Rohrabacher, a former speechwriter for Ronald Reagan and a candidate for Trump's cabinet, was often criticised for his apparent close relationship with Russia and its president Vladimir Putin.

He was frequently accused of relying on his position in Congress to subvert US foreign policy with outside interests.

On a 2016 audio capture of an exchange between then-House Majority Leader Kevin McCarthy and other Republicans, Mr McCarthy can be heard joking that Mr Rohrabacher and Mr Trump are on Russia's payroll.

Months before Mr Trump was elected president – and the day after the Washington Post revealed that Russia had hacked the Democratic National Committee – Mr McCarthy was recorded telling a private meeting of fellow GOP members: "There's two people I think Putin pays: Rohrabacher and Trump. Swear to God."

In 2017, the House Committee on Foreign Affairs restricted Mr Rohrabacher's use of foreign travel expenditures over concerns of his interests in Russia.

His ties were allegedly close enough with Russia and proved so valuable to the Kremlin that the FBI reportedly warned him that Russia believed he was an asset worthy of a code name.

Mr Rohrabacher also called for the resignation of then-US Attorney General Jeff Sessions in 2018 for his refusal to boot Robert Mueller from the investigation into Russian interference in 2016 elections, saying Mr Sessions was being "disloyal to the president and to the country". Mr Sessions resigned later that year.

He had previously claimed that a deal with Mr Assange would exonerate Mr Trump amid charges that Russian-backed groups contributed to that interference, ultimately benefitting the president's campaign.

Trump suggests military investigate Vindman

In that scenario, Mr Assange would have to admit that Russia was not responsible for hacking into the Democratic National Comittee's emails.

Dozens of former Trump aides and several Russian nationals and companies were indicted in charges related to Mr Mueller's subsequent investigation.