House Intelligence Committee chairman Rep. Devin Nunes (R-CA) has instructed committee staff to prepare to cite the Federal Bureau of Investigation (FBI) in contempt of Congress after the agency failed to turn over documents explaining why agent Peter Strzok had been removed from Special Counsel Robert Mueller’s Russia investigation.

Byron York of the Washington Examiner reported Saturday that the committee had subpoenaed the FBI in August for information about why Strzok was dropped from Mueller’s team. Over the next three months, the FBI repeatedly refused to turn over the requested information. Nunes met and spoke to Deputy Attorney General Rod Rosenstein, York reported, to no avail. Nunes and the committee continued to pursue the matter right up through Friday, Dec. 1.

The following day, the New York Times and the Washington Post reported that Strzok had been kicked off Mueller’s team because of anti-Trump text messages that he was found to have exchanged with FBI lawyer Lisa Page during the 2016 presidential election. Strzok had also worked on the investigation into former Secretary of State Hillary Clinton’s storage of emails, including classified information, on an illicit private server. She was not prosecuted.

In addition, Strzok and Page were found to have carried on an extramarital affair. Page worked for FBI Deputy Director Andrew McCabe, who conservatives have long complained had a conflict of interest because his wife received campaign funding from Virginia Governor Terry McAuliffe, a close ally of the Clintons for decades.

The revelation of Strzok’s removal, and the reasons for it, are a huge blow to the credibility of Mueller’s inquiry, which critics have long claimed is riddled with partisan conflicts of interest. Some of the lawyers working for Mueller had donated to Hillary Clinton, and one had even done work for the Clinton Foundation, which was a target of the Trump campaign during the election (and may have been under investigation by the FBI as well).

Nunes and the committee had known about Strzok’s removal for months, but not the reasons for it, which were only revealed on Saturday in what York suggested was an “orchestrated leak” to the Times and the Post. In a furious statement on Saturday, Nunes accused the FBI of deliberately covering up political bias on the Mueller team.

“By hiding from Congress, and from the American people, documented political bias by a key FBI head investigator for both the Russia collusion probe and the Clinton email investigation, the FBI and DOJ engaged in a willful attempt to thwart Congress’ constitutional oversight responsibility,” Nunes said, as quoted by York.

Nunes has reportedly promised to take action on the citation for contempt if the FBI does not come clean by the end of December. He will likely have the backing of Speaker of the House Paul Ryan (R-WI), who has also complained about the FBI’s apparent refusal to turn over information to the committee, especially on the degree to which it relied on the discredited “Russia dossier” that was paid for by Clinton and the Democratic National Committee.

Earlier this year, Nunes stepped back from direct involvement in the committee’s Russia investigation after questions about his role in exposing the “unmasking” of U.S. citizens in intelligence reports during the last days of the Obama administration. Democrats have stalled an ethics investigation into Nunes to keep him from resuming his role in a full capacity. However, Nunes has not given up his chairmanship and still wields the subpoena power.

During the Obama administration, Attorney General Eric Holder was found in contempt of Congress for failing to turn over documents on Operation Fast and Furious, which caused the death of Border Patrol Agent Brian Terry.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. He was named one of the “most influential” people in news media in 2016. He is the co-author of How Trump Won: The Inside Story of a Revolution, is available from Regnery. Follow him on Twitter at @joelpollak.