But the claim, which came the day after Mr. Trump pardoned numerous high-profile white-collar criminals, grabbed attention because a lawyer for Mr. Assange portrayed Mr. Rohrabacher as acting on Mr. Trump’s instructions. Previous accounts have described Mr. Rohrabacher as freelancing an idea that he came up with on his own.

On Wednesday, a lawyer for Mr. Assange, Edward Fitzgerald, referred in court to a statement by another lawyer for Mr. Assange, Jennifer Robinson, describing a purported quid-pro-quo offer conveyed by Mr. Rohrabacher, according to a Daily Beast account of a hearing on what evidence could be admitted at an upcoming extradition hearing.

The statement by Ms. Robinson, he said, described “Mr. Rohrabacher going to see Mr. Assange and saying, on instructions from the president, he was offering a pardon or some other way out” of his legal troubles if Mr. Assange “said Russia had nothing to do with the D.N.C. leaks.”

The Wall Street Journal reported in September 2017 that Mr. Rohrabacher — who lost his seat in the 2018 midterm elections — was trying to broker a deal for a pardon if Mr. Assange produced evidence absolving Russia of the hack. That would have also absolved the Trump campaign of suspicions that it conspired with Russia.

But that article portrayed Mr. Rohrabacher as approaching the White House with an idea that he had come up with, not acting as Mr. Trump’s envoy. It said that he spoke with John F. Kelly, Mr. Trump’s chief of staff at the time, about the possibility of “a meeting between Mr. Assange and a representative of Mr. Trump, preferably someone with direct communication with the president,” but that Mr. Kelly had not passed that message on to the president.