BURLINGTON, Vt. (WCAX) The White House says it's done cooperating with the impeachment inquiry.
The administration also blocked the U.S. ambassador to the European Union from testifying.
The White House calls the investigation unconstitutional. A scathing eight-page letter to top Democrats says the probe lacks a legitimate constitutional foundation.
Vermont Sen. Patrick Leahy says the president is covering something up if he won't allow the testimony.
"The fact that they are covering it up, no more people are testifying worries me. Allow them to come forward and testify. If the Trump administration has nothing to hide, then they should be willing to let people testify," said Leahy.
President Trump accused Leahy along with other senators of threatening to withhold aid to Ukraine if they didn't cooperate with the Russian investigation.
Leahy says that's not true.