Senate investigators have reportedly interviewed a whistleblower at the Internal Revenue Service who has said the audit of the president or the vice president was the subject of improper political interference. The Washington Post reports that the whistleblower’s complaint alleges that at least one political appointee at the Treasury Department may have tried to tamper with an IRS audit of Donald Trump or Mike Pence. The interview is reported to have happened in recent weeks, and the whistleblower gave transcribed remarks to the offices of Sens. Charles E. Grassley (R-IA) and Ron Wyden (D-OR), who are the chairman and highest-ranking Democrat on the Senate Finance Committee. The complaint was first disclosed in an August court filing by Rep. Richard Neal (D-MA), the chairman of the House Ways and Means Committee, as part of his lawsuit against the Trump administration to force the release of the president’s tax returns.