ActBlue is fighting back against a House Republican investigation into its workings, saying the probe appears to have become an unconstitutional abuse of power to help the White House.

The Democratic online fundraising platform said Monday in a letter obtained by POLITICO that it was reevaluating whether to cooperate with the ongoing congressional investigation into fraud on its platform in light of President Donald Trump’s executive action to investigate potential foreign contributions on ActBlue and House Republicans’ public statements supporting the White House.

“If the Committees are now working to gather information on behalf of Department of Justice prosecutors, rather than for legitimate legislative purposes, that would fundamentally transform the nature of your investigation — and violate ActBlue’s constitutional rights,” ActBlue’s lawyers wrote in the letter Monday to GOP Reps. Jim Jordan, James Comer and Bryan Steil.

The allegations are an escalation in the conflict between House Republicans and ActBlue, the behemoth Democratic fundraising platform that has long been in GOP crosshairs as it has helped the left build a massive fundraising advantage. ActBlue CEO Regina Wallace-Jones told Blue Light News last month that ActBlue believes the platform has “nothing to hide” but needs to better communicate its role in light of the attacks.

In the letter, lawyers representing ActBlue ask the congressional committees investigating the platform to clarify the purpose of their work. They argue public statements from Jordan, Comer and Steil indicate they are seeking to help the Trump Justice Department’s separate investigation into ActBlue, rather than carry out congressional oversight.

And they note that the “selective focus” of the investigation does not appear to include WinRed, the GOP’s primary online fundraising counterpart — and thus may be intended to hurt Democrats, not provide legitimate oversight of American elections.

“The Committees’ selective focus on ActBlue also suggests that the investigation may be a partisan effort directed at harming political opponents rather than gathering facts to assist in lawmaking efforts,” the letter reads. “Such an action would raise substantial First Amendment concerns.”

Spokespeople for the GOP committees investigating ActBlue did not immediately respond to requests for comment Monday afternoon. A spokesperson for ActBlue also did not immediately comment.

The letter comes as the Trump administration is also going after ActBlue. Trump signed a memorandum in April ordering Attorney General Pam Bondi to investigate the potential use of foreign “straw” donations in online fundraising, citing concerns about foreign influence in elections based in part on the work of the GOP-led congressional committees. ActBlue was the only platform named in the order. The memorandum calls for Bondi to report back in 90 days, which would be late July.

Under federal law, only U.S. citizens and green card holders can give to campaigns and political action committees. Republicans have long argued that ActBlue, which processed billions of dollars in donations for Democrats last year, is not strict enough in weeding out potential foreign contributions. ActBlue has countered that it has processes to catch illegal donation attempts and that similar challenges exist on other platforms, including WinRed.

The platform’s lawyers also suggested that ActBlue’s further cooperation with the congressional probes could depend on the extent of the committees’ work with the Justice Department.

“In light of your public statements, it is essential that we receive more information about your agreement to coordinate the Committees’ activities with the Executive Branch, so that ActBlue may properly evaluate its ongoing efforts to cooperate with the Committees,” the platform’s lawyers wrote.

ActBlue previously turned over thousands of pages of internal documents to the committees, some voluntarily, and then later under subpoena. The committees released an interim report in April that cited cases of fraud identified in the ActBlue documents as a means to argue that the platform had an “unserious” approach to fraud prevention.