An Internal Revenue Service official has filed a whistleblower complaint reporting that he was told at least one Treasury Department political appointee attempted to improperly interfere with the annual audit of the president or vice president’s tax returns, according to multiple people familiar with the document.

Trump administration officials dismissed the whistleblower’s complaint as flimsy because it is based on conversations with other government officials. But congressional Democrats were alarmed by the complaint, now circulating on Capitol Hill, and flagged it to a federal judge. They are also discussing whether to make it public.

The complaint has come amid the escalating legal battle between the Treasury Department and House Democrats over the release of President Trump’s tax returns. Part of that inquiry from Democrats is over how the IRS conducts its annual audit of the president and vice president’s tax returns. That process is supposed to be walled off from political appointees and interference.