According to The Washington Post, “Two senators are looking into a whistleblower’s allegations that at least one political appointee at the Treasury Department may have tried to interfere with an audit of President Trump or Vice President Pence, according to two people with knowledge of the matter, a sign that lawmakers are moving to investigate the complaint lodged by a senior staffer at the Internal Revenue Service.”

It could not be learned to what extent the senators consider the whistleblower a credible source. Trump administration officials have previously played down the complaint’s significance and suggested that it is politically motivated.

The whistleblower, a career IRS official, initially filed a complaint in July, reporting that he was told that at least one Treasury political appointee attempted to improperly interfere with the annual audit of the president’s or vice president’s tax returns. In recent weeks, the whistleblower filed additional documentation related to the original complaint, which was given to congressional officials in July, the two people said. These people spoke on the condition of anonymity because of the sensitivity of the complaint, which pertains to a confidential IRS audit that cannot be disclosed under federal law.