Fusion GPS, the opposition research firm behind the infamous Trump dossier, says it will not comply with subpoenas for documents and testimony issued earlier this month by the House Intelligence Committee.

In a Monday letter to the committee, Fusion’s attorneys argue that the subpoena, which seeks testimony from three of the firm’s partners, violates its First Amendment privileges and would force it to break attorney-client privilege and its contractual obligations.

The lawyer, Josh Levy, also argued that forcing Fusion GPS to comply with the subpoenas would “chill any American running for office” from conducting political opposition research.

Fusion GPS began investigating Trump in September 2015 at the financial discretion of an unidentified Republican donor who opposed the real estate billionaire. After Trump won the GOP nomination, an unidentified Democratic ally of Hillary Clinton’s hired Fusion. Fusion then hired former British spy Christopher Steele to investigate Trump. The result is the dossier, which remains largely uncorroborated.

“We cannot in good conscience do anything but advise our clients to stand on their constitutional privileges, the attorney work product doctrine and contractual obligations,” Levy, the Fusion lawyer, wrote to California Rep. Devin Nunes, the committee’s Republican chairman. Business Insider first reported details of the letter.

The subpoena calls for testimony from Fusion GPS co-founders Glenn Simpson, Tom Catan and Peter Fritsch. The trio started the Washington, D.C.-based Fusion GPS after leaving The Wall Street Journal.

But Levy says that the Fusion partners will refuse to testify even if compelled by Congress.

“Should you compel any of our three clients to appear at the scheduled deposition, they will invoke their constitutional privileges not to testify,” Levy wrote in the letter.

A congressional official responded to Fusion’s letter, telling The Daily Caller that “Fusion GPS is refusing to answer questions about the Steele dossier — that’s the bottom line.”

“If they have nothing to hide, they should simply answer the questions, and then Congress can move on,” the official said.

Fusion’s letter marks the second time that the firm has said it will ignore congressional subpoenas related to the dossier. In August, Fusion said it would not comply with subpoenas issued by the Senate Judiciary Committee, which is also investigating certain aspects of the Steele report, which BuzzFeed published Jan. 10.

Simpson had been invited by the committee to testify at a hearing over the summer, but he said that he would refuse to attend. The committee ultimately rescinded its subpoena after Simpson agreed to a closed-door interview Aug. 22. Fusion also turned over documents in response to that request from Judiciary, though a spokesman for the committee said that the information was useless and mostly consisted of news clippings. (RELATED: Fusion GPS Turns Over Documents To Senate Panel, But There’s Just One Problem)

Republicans are interested in several aspects of the dossier, including the identity of Fusion GPS’ clients, Steele’s sources, and how much federal investigators relied on the document to form the basis of the collusion investigation into Trump associates.

Nunes and Grassley have pressed Fusion GPS on those questions, while also demanding answers from the FBI and Justice Department regarding their handling of Steele’s research. Grassley has said he is concerned that the FBI relied on a controversial document compiled as part of a political opposition research project to kickstart its investigation into the Trump campaign.

U.S. officials reportedly cited the dossier in an application for a foreign intelligence surveillance warrant against former Trump campaign adviser Carter Page. The FBI also reportedly agreed to pay Steele $50,000 to continue his investigation into Trump. Grassley has asked the FBI for details on that agreement, which reportedly never materialized.

Nunes has also subpoenaed FBI Director Christopher Wray and Attorney General Jeff Sessions to find out how much those agencies relied on the dossier to form the basis of the federal investigation of possible collusion between the Trump campaign and Russian government. So far, the agencies have refused to produce the documents.

Democrats have blasted the focus on the dossier, accusing Republicans of attempting to smear Steele and Fusion GPS in order to protect Trump.

But Republicans have shot back, questioning why Democrats appear to not want to find out whether the dossier was vetted by federal investigators.

“I don’t know why anyone … would not be curious whether or not the world’s premier law enforcement agency relied upon a dossier in connection with an investigation without vetting it,” South Carolina Rep. Trey Gowdy, a Republican member of the House Intel Committee, told The Daily Caller in an interview last month. (RELATED: Gowdy Wonders Whether Dossier Is ‘A Piece Of Fiction’)

“Before you can rely on something, you need to know where it came from and how it was either corroborated or contradicted,” Gowdy said, adding that “it is relevant to ask whether or not a law enforcement agency relied on this dossier — or any evidence — without vetting it.”

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