A reputed mobster is trying to wriggle out of a guilty plea by claiming he didn’t think the prosecutor would push for maximum prison time.

Reputed Gambino associate Battista “Benny” Geritano admitted in court that he threatened to behead his ex-lawyer’s son.

But he’s now saying he wouldn’t have copped to the single charge of mailing a threatening communication if he’d known Assistant US Attorney Lindsay Gerdes would seek to have him locked up for life.

He wants Gerdes removed from the case.