The founders of Fusion GPS, the research firm behind the "Steele dossier," said that congressional Republicans are "chasing rabbits" in an op-ed published Tuesday in The New York Times.
The op-ed, titled "The Republicans' Fake Investigations," is the first in-depth account given by the Fusion GPS founders, Glenn R. Simpson and Peter Fritsch, outside of a courtroom or a private committee hearing.
"The intelligence committees have known for months that credible allegations of collusion between the Trump camp and Russia were pouring in from independent sources during the campaign," Simpson and Fritsch wrote. "Yet lawmakers in the thrall of the president continue to wage a cynical campaign to portray us as the unwitting victims of Kremlin disinformation."
The two former journalists wrote that they have "toppled the far right's conspiracy theories" and that they did not believe their firm's dossier was the trigger for the FBI's investigation into alleged collusion between the Trump camp and Russia.
Fusion GPS hired former British spy Christopher Steele to conduct research on Donald Trump's possible connections to Russia during the 2016 presidential campaign. That research — compiled in a series of memos referred to as the "Steele dossier" — has inflamed Republicans who contend the unverified reports were the basis of the federal investigation into Trump's campaign.
The op-ed follows a report published in the Times on Saturday that confirmed that the dossier was not the cause of the FBI inquiry now being headed by special counsel Robert Mueller.
Lawmakers on the House Intelligence Committee are fighting Fusion GPS in court to acquire the company's bank records. In filings with the U.S. District Court in Washington, D.C., attorneys for the committee have argued that Fusion GPS has sought to keep records from the committee that are relevant to its investigation.
Fusion GPS has argued the records the intelligence panel is looking for are not pertinent to its investigation. In their op-ed, Simpson and Fritsch accuse the committee of going on a "fishing expedition for the records of companies we work for that have nothing to do with the Trump case."
Thomas Hungar, general counsel of the House of Representatives, did not respond to a request for comment from CNBC.
The writers, who note that their firm provided 21 hours of testimony to congressional committees, called on Congress to release the transcripts of their testimony "so that the American people can learn the truth about our work."
Senate Judiciary Committee Chairman Chuck Grassley, R-Iowa, said his panel has provided Fusion GPS with multiple opportunities for transparency.
"Senator Grassley provided Fusion GPS an opportunity for transparency six months ago when he invited the firm to publicly testify at an open committee hearing. Mr. Simpson declined. When faced with a subpoena from the Chairman and Ranking Member, Mr. Simpson refused to provide public testimony," Grassley's office wrote in a statement provided to NBC News. "Despite his public statements, Mr. Simpson and his attorney demanded during the interview that the transcript be kept confidential."
"The Committee's invitation for Mr. Simpson to testify at a public hearing remains on the table," the statement said.
Senate Intelligence Committee Chairman Richard Burr, R-N.C., said Wednesday that "if Mr. Simpson and Mr. Fritsch would like to return to the Committee for an open hearing, we will certainly entertain such an event."
A spokesperson for Fusion GPS did not respond to a request for comment from CNBC.
Read the full op-ed at The New York Times.