USC's Steve Sarkisian -- Powerful Alums & Boosters Pissed ... Calls to Fire Coach

The backlash over Steve Sarkisian's drunken comments at a USC event has begun -- with several high-powered alums and boosters calling for the school to fire the coach ... TMZ Sports has learned.

Multiple high-ranking USC sources tell us ... ever since reports surfaced about the USC head football coach slurring and cussing at a major USC function Saturday night, the powers that be at SC have been getting complaints from the people who back the program.

One high-ranking USC source tells us ... "I've been getting a flurry of phone calls this morning from people who want him out. They feel he's an embarrassment to the program and the community."

Sarkisian has already apologized for his behavior -- and says he has assured SC's athletic director that it won't happen again.

We're told Sark has NOT yet addressed the football team over the incident -- but he's planning on speaking with the players about it.

We spoke to the parents of one USC football recruit who also tells us they're disappointed by Sark's actions -- but were NOT pulling their kid from the program over it.