Is a defendant entitled to access to counsel at trial if counsel is engaged in a conflict of interest?

interest that undermines counsel's loyalty to his or her client. [Citations.] 'It has long been held that under both Constitutions, a defendant is deprived of his or her constitutional right to the assistance of counsel in certain circumstances when, despite the physical presence of a defense attorney at trial, that attorney labored under a conflict of interest that compromised his or her loyalty to the defendant.' [Citation.] 'As a general proposition, such conflicts "embrace all situations in which an attorney's loyalty to, or efforts on behalf of, a client are threatened by his responsibilities to another client or a third person or his own interests. [Citation.]"' [Citations.]" (People v. Doolin (2009) 45 Cal.4th 390, 417; accord, People v. Bonin, supra, 47 Cal.3d at p. 835.)