WASHINGTON — The Bush administration rushed to revamp the largest U.S. bailout plan in history Monday, working with executives of the nation’s biggest banks to shift and shape new pieces and get desperately needed credit flowing. Stocks soared around the world in response to dramatic efforts here and overseas — and the possibility of even bolder American action.

Scrambling to catch up with events, Treasury Secretary Henry Paulson, Federal Reserve Chairman Ben Bernanke and the bankers were modeling many parts of their revamped program after strong initiatives in Europe, where governments put $2.3 trillion on the line Monday in guarantees and other emergency measures to save banks there.

Elements being considered for the overhauled U.S. program included not only the details for purchasing banks’ bad assets — the major feature of the $700 billion bailout bill that sped through Congress — but also direct government purchases of stock in banks, an idea that Paulson surfaced only last week.

Another initiative under consideration: providing government guarantees for the short-term loans banks make to each other, a vital credit avenue that has come under severe stress as fears have mounted over the hundreds of billions of dollars of losses that began with the meltdown of the subprime mortgage market in the United States more than a year ago.

Major stock markets around the world surged higher after last week’s market disaster as traders began to hear of Europe’s actions and the possibility of further steps in the United States.