President-elect Donald Trump's incoming chief of staff Reince Priebus said Rep. John Lewis' criticism of Trump was "irresponsible" and called on President Obama to "step up" by telling Democrats to accept the election loss and stop questioning "the legitimacy of the next United States president."
In an interview on "This Week," ABC News' George Stephanopoulos asked Priebus if the president-elect was right to pick a fight this weekend over remarks by Congressman and civil rights icon Lewis.
"John Lewis stood up in an interview and said that Donald Trump was not a 'legitimate president,'" Priebus said, referring to an NBC interview on Friday. "That's insanity, and it's wrong."
"We need folks like John Lewis and others who I think have been champions of voter rights to actually recognize the fact that Donald Trump was duly elected. He's going to put his hand on the Bible in five days," Priebus said.
"I think it's incredibly disappointing -- and I think it's irresponsible -- for people like [Lewis] to question the legitimacy of the next United States president," he added. "I think putting the United States down across the world is not something a responsible person does."
The incoming White House chief of staff added that Director of National Intelligence James Clapper has said "many, many times" there's no evidence that Russia's interference in the presidential election affected the outcome.
Clapper has said that the intelligence community can't gauge how voters' choices in the election might have been affected by the disclosure of private information stolen by hackers.
"President Obama should step up," Priebus said. "We've had a great relationship with the White House, George ... I think the administration can do a lot of good by telling folks that are on the Republican side of the aisle, 'Look, we may have lost the election on the Democratic side, but it's time to come together.'"