A 5 billion euro ($5.33 billion) rescue plan for Italian bank Monte dei Paschi di Siena hung by a thread on Monday after Prime Minister Matteo Renzi's defeat in a referendum tipped the country into political turmoil. The world's oldest bank, saddled with 46 billion euros of bad loans, needs to raise the money by the end of the month to avoid being wound down, but Italy could now face early elections after Renzi said he would quit to take responsibility for the defeat of his constitutional referendum. Monte dei Paschi, rated the weakest lender in European stress tests this summer, had planned to secure a firm commitment from one or more anchor investors and launch a share sale as early as Wednesday or Thursday.