A member may change his vote only if he or she makes a timely request to do so immediately following the announcement of the vote by the city clerk and prior to the time that the next item in the order of business is taken up. A council member who publicly announces that he or she is abstaining from voting on a particular matter may not subsequently withdraw his abstention. (Ord. No. 935, § 2 (part); Ord. No. 1317, § 2 (part).)