Bankruptcy Judge Thomas Bennett yesterday delayed by at least a month a decision to set a deadline for bankrupt Jefferson County, Ala., to a workout plan demanded by a creditor, Reuters reported yesterday. Saying that the $4.23 billion case, the largest U.S. municipal bankruptcy ever, was immensely complicated, Judge Bennett told lawyers in a hearing he would schedule a status conference on the deadline request by Assured Guaranty Municipal Corp for an unspecified day in mid-September. Bond-insurer Assured, which has $709 million of exposure to defaulted Jefferson County sewer-system warrants and other debt, argues that cash-strapped Jefferson County has been slow in developing a so-called plan of adjustment to exit chapter 9 and needed a fixed deadline of Sept. 28. The county, along with unsecured creditors, argued that a quick exit plan is impossible because significant financial issues, such as possible rate hikes for the sewer system at the heart of other bankruptcy, remain outstanding.