Sen. Tom Cotton, R-Ark., unloaded on the inspector general at the center of the anti-Trump whistleblower kerfuffle, calling him “insolent” and “obstructive” in a scathing letter released on Wednesday afternoon.

Michael Atkinson, the Intelligence Community Inspector General, or ICIG, is under fire for secretly eliminating a requirement that whistleblowers provide first-hand information to support allegations of wrongdoing. The ICIG admitted that it secretly changed its rules and forms in response to an error-ridden complaint filed against President Donald Trump that consisted entirely of gossip, rumor, and second-hand information.

“Your disappointing testimony to the Senate Intelligence Committee on September 26 was evasive to the point of being insolent and obstructive,” Cotton, a Republican member of the Senate Select Committee on Intelligence (SSCI), wrote on Wednesday.

Cotton said Atkinson refused to disclose to SSCI members why Atkinson initially determined the anti-Trump complainant had a partisan political bias against Trump.

“Despite repeated questions, you refused to explain what you meant in your written report by ‘indicia of an arguable political bias on the part of a rival political candidate,'” Cotton wrote. “This information is, of course, unclassified and we were meeting in a closed setting. Yet you moralized about how you were duty bound not to share even a hint of this political bias with us.”

“But now I see media reports that you revealed to the House Intelligence Committee not only that the complainant is a registered Democrat, but also that he has a professional relationship with a Democratic presidential campaign,” Cotton continued. “I’m dissatisfied, to put it mildly, with your refusal to answer my questions, while more fully briefing the three-ring circus that the House Intelligence Committee has become.”

Cotton demanded that Atkinson disclose the exact nature and examples of the anti-Trump complainant’s partisan political bias against the president, and to disclose whether Atkinson or his staff communicated to anyone at CNN that the sole basis for the political bias finding against the complainant was a Democratic voter registration. Ahead of Atkinson’s testimony in the House, CNN’s Jake Tapper falsely asserted, citing a “source familiar with the investigation prompted by the whistleblower,” that the complainant’s voter registration was the sole evidence of the complainant’s political bias.

“Did you or anyone subject to your control or influence share with CNN that the ‘arguable political bias’ was merely that the complainant is a registered Democrat?” Cotton asked. He also directed Atkinson to disclose the anti-Trump Democratic presidential candidate with whom the complainant had a professional relationship.

“This information is also simple, unclassified, and personally known to you,” Cotton wrote. “Therefore please reply in writing no later than 5:00 p.m. on Friday, October 11.”

“I look forward to your answers, even two weeks late,” Cotton concluded.

You can read the entirety of Cotton’s letter here.