According to the Washington Examiner, discussions with the whistleblower - revealed by RealClearInvestigations as 33-year-old Eric Ciaramella have been halted, "and there is no discussion of testimony from a second whistleblower, who supported the first's claims."

Ciaramella complained that President Trump abused his office when he asked Ukraine to investigate corruption allegations against Joe Biden and his son Hunter, as well as claims related to pro-Clinton election interference and DNC hacking in 2016.

On Thursday, a top National Security Council official who was present on a July 25 phone call between Trump and Ukrainian President Volodomyr Zelensky testified that he saw nothing illegal about the conversation.