back channel

But clearly with Gaetz, Trump was given a clear — if “back channel” — message that the nomination was “not going to work.”

She added that China may also be "likely worried that that they lack reliable back channels to influence Trump's policy".

“This sort of trouble is always handled through back channels,” Nam said.

During an early 2000s bird flu outbreak in Vietnam, farmers circumvented regulations by moving poultry at night, bribing inspection workers, and selling their goods through back channels.

Another email directly used the phrase "back channel" — a key part of prosecutors' argument about Costello's role.