Michael Atkinson, inspector general for the U.S. intelligence community, needs to be completely forthright about inconsistencies in a key form related to the Ukraine whistleblower's complaint, U.S. Rep. Devin Nunes said Wednesday night.

Nunes, a California Republican who serves as ranking member of the House Intelligence Committee, said on "The Ingraham Angle" that his GOP colleagues on the panel wrote to Atkinson in September, complaining about relevant forms that didn't match, and that the investigator responded in "an inadequate way" a week later.

"From the time that the whistleblower first came forward, to the IG, where the forms didn't match, it wasn't urgent, didn't have any firsthand knowledge, the form later changed, then it was backdated, ... then we had to hear from the whistleblower and then we didn't have to hear from the whistleblower," Nunes said.

HOUSE INTEL REPUBLICANS INVESTIGATION INSPECTOR GENERAL HANDLING OF WHISTLEBLOWER COMPLAINT

"The very origins of this investigation are shady and don't make any sense," he added of the probe into President Trump and Ukraine.

When host Laura Ingraham referenced past pointed criticisms of Nunes, the lawmaker brushed them off.

"If they think I'm going to go away, I'm not," he responded.

"If they think I'm going to go away, I'm not." — U.S. Rep. Devin Nunes, R-Calif.

He said that if he were Atkinson, he would provide full documentation to prove there was nothing nefarious going on in September.

"You have to either believe he is in on it or he is incompetent," he said, adding Atkinson's October 2019 response letter could be characterized as him being indeed "incompetent."

"If he's incompetent ... we need to have evidence of your incompetence. ... We are not going to take your word for it that, 'Oh, we made a mistake'," he added.

Republicans for weeks have complained that the whistleblower made contact in advance with the staff of House intel panel Chairman Adam Schiff -- though Schiff, a California Democrat, has downplayed the nature of that contact.

Whether Republicans are looking further into that contact as part of their review was unclear. But since last fall, they have specifically challenged intelligence community officials over changes to a key form that dropped a requirement for “firsthand information” in whistleblower complaints.

The White House released a declassified version of the complaint, which revealed that the whistleblower’s concerns stemmed from second-hand accounts from “more than half a dozen U.S. officials.”

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After the form change was first noticed in media reports, Atkinson said in a lengthy statement that the whistleblower had actually filled out the older version of that form, which retained the requirement that whistleblowers have first-hand information. The ICIG revealed that the whistleblower had said he or she had first-hand information, as well as second-hand information, but it was unclear what the first-hand information was.

Fox News' Brooke Singman contributed to this report.