The Iran arms-and-hostages deal, ballooning into the most serious crisis of Ronald Reagan's presidency, has prompted some of Reagan's longtime California confidants to urge a major shake-up in the Administration-apparently beginning with the departure of Chief of Staff Donald T. Regan and national security adviser John M. Poindexter.

Revelations last week suggested that Reagan might not have been fully informed from the outset about the full details of his Administration's dealings with Iran over arms and hostages. And the possibility that lower-level officials could have sidestepped the President in managing such an explosive foreign policy issue raises questions about Reagan's control over his foreign policy apparatus.

Chief of Staff Regan-who overruled other aides in advising Reagan not to admit he had made a mistake in ordering arms shipments to so-called Iranian moderates-has made a point of emphasizing that Reagan has taken full responsibility for the Iranian mission. "It was a courageous thing for him to do," said Regan. "We all allowed him to do it."