If he cannot apply enough public pressure to move Congress, he will try to move 2012 voters to give him a mandate.

White House aides saw the shift after handing the president his speech for last week’s appearance at a factory in Michigan, as economic advisers monitored post-downgrade gyrations on Wall Street and the full-blown debt crisis in Europe.

Mr. Obama thought the draft speech was too soft on the Republicans — and so he personally sharpened it. The result: a famously “cool” president delivered the hottest rhetoric of his tenure, blistering opponents for refusing “to put the country ahead of party” because they would “rather see their opponents lose than see America win.”