Rep. Devin Nunes, R-Calif., went further than Attorney General William Barr to answer the question of when special counsel Robert Mueller knew there was no collusion between the Trump campaign and Russia.

In an interview that aired Friday on Fox News, Barr said he "couldn't say."

Appearing after Barr, Nunes, the ranking member of the House Intelligence Committee, was not so hesitant.

"Bob Mueller knew the day that he walked in the door there was no evidence of the Trump campaign colluding with Russians," Nunes said, referring to the findings of the FBI's counterintelligence that began in the summer of 2016. Mueller was appointed to lead the investigation into Russian interference in the presidential election in May 2017, eight days after President Trump fired former FBI Director James Comey.

Although Mueller completed his investigation in March, Nunes said the House Intelligence Committee, which conducted its own Russian interference investigation when he was chairman, determined there was no collusion by early 2018.

"I'm able to answer that because we looked at all the work. We looked at all the intelligence. We've known for — our report came out a year ago. There's zero evidence of the Trump campaign colluding with Russians — period," Nunes said.

[Related: Trump: 'Investigate the Investigators!' ]

Despite Nunes' decisiveness, Democrats on the House Intelligence Committee argued the investigation was wrapped up prematurely. Since taking back control of the House, they have restarted the Trump-Russia investigation.

Fox News anchor Sandra Smith repeatedly challenged Nunes on that point, noting that Barr has not publicly said when the collusion question was solved by Mueller.

"That's my point. I just wanted to make sure that I answered it for the American people and that's why the attorney general is doing a good job here is he's not jumping to any conclusions," Nunes said.

The Justice Department released Mueller's 448-page report with redactions last month, which noted the term "collusion" has no legal application. Instead, Mueller's team focused on analyzing the prospect of criminal conspiracy.

Mueller concluded that Russia used cyberattacks and social media disinformation campaigns to interfere in 2016, but he did not establish any criminal conspiracy between the Russian government and the Trump campaign. Republicans have long alleged that the launching of the investigation into Trump in 2016 was influenced by politics and that the investigation itself was rife with misconduct.