Grubbs declined to elaborate on Johnson's relationship with Rohrabacher.
The release of the emails put Democratic candidate Hillary Clinton on the defensive and are among the incidents that led to investigations by the Justice Department and multiple House and Senate committees into potential ties between President Trump's campaign and election meddling.
Assange's claim contradicts the widely accepted assessment of the USA intelligence community that the thousands of leaked emails, which indicated the Democratic National Committee rigged the nomination process against Sen. The congressman plans to divulge more of what he found directly to President Trump.
Rohrabacher added that he believes the information Assange shared with him "will have an earth-shattering political impact".
As for other information to be given to the president, Rohrabacher said: "We left with the understanding that we would be going into further details in the near future".
Multiple U.S. intelligence agencies have agreed Russian Federation was involved in the theft of Democratic Party emails and tried to influence the 2016 election to benefit Trump. "He can't even leave the embassy to get out to Washington to talk to anybody if he doesn't have a pardon".
Assange has taken asylum at Ecuador's London embassy since 2012 to avoid extradition to Sweden on sexual assault charges, which he has maintained is a ruse to get him extradited to the United States for publishing troves of US government documents leaked by Chelsea Manning in 2010 - although there are no formal charges or extradition orders yet. "He has given us a lot of information".
"Unbeknownst to me I am the first member of Congress to visit there with Mr. Assange", he said.
Rep. Rohrabacher is the Chairman of the House Foreign Affairs Committee's Subcommittee on Oversight and Investigations, a position which might be of considerable import amid multiple Congressional investigations into the allegations of Russian Federation being behind the leaks.
Grubbs also said Rohrabacher paid for the trip to London - which he took while many of his House colleagues are working and holding town hall meetings in their districts - with personal funds.