Some cops in Beverly Hills aren't happy Erik and Lyle Menendez could possibly be released ... with some officers going as far as blasting it as a political move.

Law enforcement sources tell TMZ ... several officers with the Beverly Hills Police Department -- the city where the murders occurred -- say Los Angeles County District Attorney George Gascón is trying to win political points by letting the brothers out of prison.

He's fallen behind in the polls to his opponent for the position, Nathan Hochman, and some officers see this as a big swing to get himself back in the race.

It's not that cops don't necessarily believe the brothers' claims their dad Jose abused them, our sources say ... they're just don't think that justifies the brutal shotgun murders of their parents.

We're also told many cops at BHPD weren't working when the murders went down, so they don't know the case all that well or care as intensely about this case as older veterans.

That said, we're told the cops with knowledge of the case stand by their earlier investigation ... saying they did their job and this is now the D.A.'s issue.

In just a few hours, the D.A. will announce whether he will try to free the brothers. Gascón could go two ways -- either ask a judge to resentence Erik and Lyle, or ask the judge to set aside the murder conviction and impose a voluntary manslaughter conviction.

The maximum in Cali for voluntary manslaughter is 11 years, and the brothers have served nearly 35 years ... so if the judge signs on, they would be released. He will announce his decision during a news conference set for 1:30 PM PT.