Senate aides spoke to the whistleblower, and follow-up interviews are expected.
Staff members for Sens. Charles E. Grassley (R-Iowa) and Ron Wyden (Ore.), the chairman and ranking Democrat on the Senate Finance Committee, met with the IRS whistleblower earlier this month, those people said. Follow-up interviews are expected to further explore the whistleblower’s allegations.
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.