under this subsection may be extended for any number of additional 30-day periods upon written request by the Administrator or the head of the agency. Such request shall be granted unless the nonrequesting party denies the request in writing within 5 days after receipt of the request for extension. (6) Return If the Administrator determines OIRA is unable to complete a review within the time period described under this subsection, the Administrator may return the draft of the significant regulatory action to the agency with a written explanation of why OIRA was unable to complete the review and what additional information, resources, or time OIRA would need to complete the review. (7) Withdrawal An agency may withdraw the regulatory action from OIRA review at any time prior to the completion of the review. (e) Compliance review The Administrator shall review any significant regulatory action submitted under subsection (c) to determine the extent to which the agency— (1) identified the problem that the significant regulatory action is designed to address (including, where applicable, the failures of private markets or public institutions that warrant new agency action)