Congressman Devin Nunes filed a federal lawsuit Wednesday against opposition research firm Fusion GPS, its founder Glenn Simpson, and left-leaning watchdog group Campaign for Accountability, accusing them of “racketeering” and interfering with his congressional Trump-Russia investigation.

Nunes, chairman of the House Intelligence Committee until Democrats won the majority in 2018, claimed that Simpson, Fusion GPS, and the Campaign for Accountability illegally conspired to “harass” him in an attempt to “hinder, delay, prevent, or dissuade” him from looking into issues surrounding the federal investigation into the Trump campaign and the Russian government, and to scare him off from investigating possible wrongdoing by Simpson and Fusion GPS.

The California Republican is asking the judge to award him $9.9 million in damages.

The 35-page complaint Nunes filed in the Eastern District of Virginia today pointed to a Daily Caller article from early August that revealed the Campaign for Accountability hired Fusion GPS as an “independent contractor” in 2018 and paid the firm close to $140,000 for research. And the Nunes lawsuit alleged the watchdog group and the opposition research firm then colluded to target him and stymie his efforts, pointing to three ethics complaints filed by the Campaign for Accountability allegedly “in concert with” Fusion GPS in an effort to “chill reporting of Fusion GPS and Simpson’s wrongdoing” and to dissuade Nunes from making criminal referrals to the Justice Department.

Nunes described Fusion GPS as “a political war room for hire that specializes in dirty tricks and smears” and the Campaign for Accountability as a “dark money, partisan, left-wing” nonprofit that he said targets mainly conservatives.

Daniel Stevens, the executive director for the Campaign for Accountability, told the Washington Examiner, “We look forward to vigorously defending ourselves against this obviously frivolous and baseless lawsuit.”

"Rather than defend his unethical conduct, Devin Nunes is trying to muddy the waters by attacking an independent watchdog group," Stevens said. "Since Nunes can't explain away these ethical lapses, he has resorted to filing poorly drafted lawsuits to deflect attention."

Stevens told the Daily Caller in August that his organization “did not hire Fusion to look into Devin Nunes or coordinate with the firm regarding our ethics complaints against Devin Nunes.”

Fusion GPS did not immediately respond to a request for comment from the Washington Examiner.

Fusion GPS was hired by the Clinton campaign and the Democratic National Committee in 2016 through the Perkins Coie law firm, and the opposition research firm in turn hired British ex-spy Christopher Steele, who made salacious allegations regarding President Trump and Russia in an unverified dossier. Marc Elias, a Perkins Coie lawyer and the Clinton campaign’s general counsel, provided briefings to the Clinton campaign related to what Fusion GPS and Steele had uncovered. The DOJ and FBI also made extensive use of Steele’s information to target Trump campaign associate Carter Page with surveillance through the Foreign Intelligence Surveillance Court. Nellie Ohr, the wife of high-ranking DOJ official Bruce Ohr, was also a contractor for Fusion GPS in 2015 and 2016, and her Trump-Russia research was passed along by her husband to the FBI.

Some of these revelations, including the payment scheme between the Clinton campaign and Fusion GPS, were revealed in connection to efforts by Nunes in 2017 and 2018.

After the Mueller report was released in April, Fusion GPS continued to insist to the Washington Examiner that “to our knowledge, nothing in the Steele memoranda has been disproven.”

Nunes said Simpson and Fusion GPS “shared a common goal” with the Clinton campaign of “using the false and defamatory statements in the Steele dossier to poison the minds of voters.”

“Fusion GPS and Simpson harbored spite and ill-will towards [Nunes] and decided to smear [him] as a result of his tenacious efforts in 2017 to expose Fusion GPS’ nefarious activities,” the lawsuit alleges.

Nunes said Fusion GPS retaliated through the Campaign for Accountability because of subpoenas he issued in 2017 to the FBI and DOJ for information on their relationship with Steele, to Simpson and other Fusion GPS partners to compel their testimony, and to the bank Fusion GPS used, which “revealed that the Clinton campaign, the DNC and Perkins Coie paid for Fusion GPS’ anti-Trump research.”

Nunes claimed that “corrupt acts of racketeering are part of [Fusion GPS’] regular way of doing business" and said “that way of doing business must end here and now.”

Justice Department Inspector General Michael Horowitz's report on the use of Steele’s dossier and alleged abuse of the Foreign Intelligence Surveillance Act, which started more than a year ago, is expected in September or early October. The DOJ watchdog’s report harshly criticizing former FBI Director James Comey over the mishandling of his memos was released last week.

This is not the only lawsuit the California lawmaker has filed this year. Nunes sued Twitter, the two parody accounts “Devin Nunes’ Mom” and “Devin Nunes’ Cow,” and Republican operative Liz Mair, claiming the social media site was letting these accounts defame him.