Annoymorously sourced BS.
That the "whistleblower" is not named, that his/her agency is not named, that no date is named, that no foreign country/leder is named, that the nature of the supposed "promise" is not named, taken together means that the MSM and Dems are floating a lurid accusation designed to preclude fact-checking.
Seen this Dem-MSM shtick many times before.