House Intelligence Committee Chairman Adam Schiff “ought to resign today” for “peddling a lie, day after day after day, unchallenged and not under oath” that the Trump campaign colluded with Russia in the 2016 presidential election, White House adviser Kellyanne Conway said.

Conway ripped the California Democrat and longtime critic of the president on ‘Fox & Friends’ Monday following the release of a letter from Attorney General Bill Barr stating that Special Counsel Robert Mueller “did not find that the Trump campaign or anyone associated with it conspired or coordinated with Russia.”

“He ought to resign today,” Conway said about Schiff. “He’s been on every TV show 50 times a day for practically the last two years, promising Americans that this president would either be impeached or indicted.”

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“Adam Schiff should resign. He has no right as somebody who has been peddling a lie, day after day after day, unchallenged and not under oath,” she added. “Somebody should have put him under oath and said ‘you have evidence, where is it’?

“Because Bob Mueller already ran the fair and the full investigation and any partisan and politicized investigation from here on in will never have the credibility of the Mueller investigation and the credibility of Attorney General Barr and Deputy Attorney General Rod Rosenstein, what they did here,” she continued.

Schiff earlier this month said he thinks a 2016 offer for dirt on Hillary Clinton by a Russian lawyer to members of the Trump campaign and the subsequent meeting is “direct evidence” of collusion on the part of the president’s team.

Last night, Schiff said he believes there is still “significant evidence of collusion” linking the Russian government with President Trump’s 2016 presidential campaign, despite reports out of the Justice Department that Special Counsel Robert Mueller will not be recommending any further indictments in his investigation.

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Conway, in her ‘Fox & Friends’ interview Monday, also said those who pushed the unsubstantiated Trump collusion narrative should apologize.

“Those who let this lie fly for two years, haranguing and harassing and trying to embarrass and worse, those of us connected to the 2016 campaign, beginning with the president and his own family really do owe people -- owe America an apology,” she said.

She also poured cold water on a Washington Post report this morning suggesting Trump plans to call for firings of media personalities and former government officials “who he believes made false accusations about him.”

And despite the large scale of Mueller’s investigation, which included interviews with around 500 witnesses, more than 2,800 subpoenas and 13 requests for foreign governments for evidence, Conway says, Trump’s critics fell short.

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“You came up with nothing -- no obstructive conduct, no collusion. No more indictments,” Conway said. “And by the way, nobody named Trump or Kushner indicted, folks. And people would whisper in our ears ‘look out, don’t be in a meeting with them, everybody has got to duck!’ I mean what a bunch of nonsense.

“You wouldn’t let the 2016 election go and now you are running up against 2020 and you got a big, ol’ nothing,” she concluded.

Fox News' Andrew O'Reilly contributed to this report.