When a defendant withdraws his plea to withdraw his plea prior to sentencing and claims his court-appointed counsel was prejudicially ineffective, what is the test for withdrawing his plea?

When the defendant moves to withdraw his plea prior to sentencing, and claims his court-appointed counsel was prejudicially ineffective, the trial court must evaluate defendant's motion under the Marsden standard and determine whether the failure to replace counsel "would substantially impair the right to assistance of counsel [citation], or, stated slightly differently, if the record shows that the first appointed attorney is not providing adequate representation or that the defendant and the attorney have become embroiled in such an irreconcilable conflict, that ineffective representation is likely to result [citation]." (People v. Smith, supra, 6 Cal.4th at p. 696.)