Management is backing the €3 billion capital increase to be completed by January but the bank's foundation, which owns a 33.5 percent stake in the lender, wants a delay until May or June.
Paying for the capital increase would hit the foundation badly and it has asked for more time to allow it to sell its shares to a third party.
The shareholders' meeting in Siena on Friday had to be postponed until Saturday because the shareholders present made up only 49.33 percent of the bank's capital - below the required 50.1 percent threshold.
The quota needed will be lowered to a third on Saturday.
A delay in recapitalization could be critical as the European Commission has demanded that the operation be completed by the end of 2014 so as to reimburse the state credits the bank received to avoid collapse.
Chairman Alessandro Profumo told the foundation in a letter that a delay would carry "grave risks" and there have been reports that he and chief executive Fabrizio Viola could resign if they do not get their way.
The head of the bank's foundation, Antonella Mansi, has said that a capital increase in January would "destroy the foundation's wealth and we cannot allow this".
The Tuscan bank, which has a proud history of independence dating back to 1472, would be nationalized if the state credits are not returned in time.
Investors were upbeat on Friday despite the storm hitting the bank and its shares rose 3.0 percent in morning trading on the Milan stock exchange.