Barack Obama's winning coalition from 2008 has crumbled and his core backers are dispirited

It's now Republicans who stand to benefit from an electorate that's again craving change. Nearly two years after putting Obama in the White House, one-quarter of those who voted for the Democrat are defecting to the GOP or considering voting against the party in power. Just half of them say they definitely will show up on election day. It's a wide enthusiasm gap that's buoying Republicans, who are poised for big electoral gains, and worrying Democrats, who are seeking to hang onto majorities in Congress as well among governors. In a reversal from 2008, Obama backers who expected change in Washington — 63% — now think nothing ever will happen. Just 36% still think Obama can do it. On the dominant issue of the 2010 campaign, just 40% of Obama backers who are fleeing Democrats say he'll be able to improve the economy over the next two years. To a certain degree, Obama's woes are a consequence of his 2008 campaign, when he was a blank slate and many people attached their hopes to him. Now, two years in, liberals, moderates and conservatives alike who supported him are disappointed for various reasons. Obama voters who are voting for Republicans or are undecided are especially doubtful about the Democratic Party's ability to handle the economy.