Does a judge have jurisdiction to resent the sentence of a criminal defendant after execution has been stayed?

Generally, a trial court loses jurisdiction "to resentence a criminal defendant after execution of sentence has begun." (People v. Howard (1997) 16 Cal.4th 1081, 1089.) Where a term of imprisonment is imposed, but execution is stayed, "the trial court retains jurisdiction, during the period a stay is in effect and at any time prior to execution of the sentence, to reconsider the sentence and vacate it or impose any new sentence which is not greater than the initial sentence." (People v. Karaman (1992) 4 Cal.4th 335, 352.)