By Silvia Aloisi SIENA, Italy (Reuters) - Italy's third-biggest bank Monte dei Paschi di Siena was forced to delay a vital 3 billion euro ($4.1 billion) share sale to raise capital until mid-2014 because of shareholder opposition, plunging its turnaround plan into uncertainty. The bank's chairman and its chief executive may now resign after their plan to launch the cash call in January was defeated at an extraordinary shareholder meeting on Saturday due to the vote of Monte Paschi's top shareholder. The unprecedented clash between the lender's executives and its main shareholder - a charitable banking foundation with close links to Siena politicians - casts a pall over a tough restructuring meant to revive its fortunes. Chairman Alessandro Profumo, a strong-willed and internationally respected banker who was formerly the chief of UniCredit, said he and CEO Fabrizio Viola would decide in January whether to step down.{br}{br}View the Entire Article{br}