“It comes from the fact that Obama as president has had to deal with all these major crises he inherited: the banks, fiscal stimulus,” said Senator Paul G. Kirk Jr., the Democrat who holds the Massachusetts seat on an interim basis pending the special election. “But for many people it was like, ‘Jeez, how much government are we getting here?’ That might have given them pause.”

Senator Evan Bayh, Democrat of Indiana, said the atmosphere was a serious threat to Democrats. “I do think there’s a chance that Congressional elites mistook their mandate,” Mr. Bayh said. “I don’t think the American people last year voted for higher taxes, higher deficits and a more intrusive government. But there’s a perception that that is what they are getting.”…

Mr. Brown has also portrayed Ms. Coakley — and by inference, her party — as acting as if she were entitled to the Kennedy seat, a perception Ms. Coakley reinforced by at first running an extremely lackadaisical campaign. With populist anger running strong, anything that smacks of establishment entitlement is politically dangerous.