What authority does a magistrate judge have to rule on a motion to withdraw consent?

In the face of this textual and historical evidence, defendants point to the grant of authority to a magistrate judge to "conduct any or all proceedings," 28 U.S.C. 636(c)(1), and argue that this "necessarily includes ruling on a motion to withdraw consent." But that grant of jurisdiction is qualified by the restriction on who may decide a motion to withdraw consent. It is a cardinal rule of statutory interpretation that a specific limitation takes precedence over a general grant of authority. See RadLAX Gateway Hotel, LLC v. Amalgamated Bank , 566 U.S. 639, 645, 132 S.Ct. 2065, 182 L.Ed.2d 967 (2012). Defendants interpretation would also have the troubling result that a party before a magistrate judge would be unable to petition an Article III judge for review. Such an arrangement would raise significant constitutional difficulties, as it would appear to lack the requisite supervision by an Article III officer.