Another factor is that most Democrats reject the notion that the long campaign will damage their chances in November. While 32 percent share this view, more, 67 percent, believe that ultimately the length of the race either won't make much difference in the general election (50 percent) or will end up helping the Democrats' cause (17 percent).
But there is an indication that the increasingly contentious race is taking a toll: In this poll, 35 percent of Americans identify themselves as Democrats, down from 40 percent last month and the lowest percentage since the primary season began.
DELEGATES – There's a brighter result for Clinton in preferences on how Democratic "superdelegates" should choose a candidate. Only 13 percent of Democrats say superdelegates should support whoever's won the most regular delegates in primaries and caucuses -- a count in which Obama's ahead, and seemingly likely to stay so.
Instead a plurality, 46 percent, say superdelegates should support the candidate who's won the most popular votes, a tally in which Clinton still has hopes. And 37 percent say superdelegates should go with their own sense of which candidate they think is best.
(Democrats who favor relying on the popular vote broadly prefer that it be based on the national vote, not the vote within each superdelegate's home state. Either way, whether to count uncontested Florida and Michigan remains a vexing point.)
DEM DAMAGE? – Significant numbers of Democrats currently say they'd defect to Republican John McCain if their candidate loses the nomination; in this poll, 21 percent of Obama's supporters, and 23 percent of Clinton's say they'd jump to McCain. But that's a result worthy of caution; it's hardly an opportune time -- in the midst of the Democrats' continuing food fight, with their dander up -- to put much stock in the result.
Still, it's clear that the Democrats' eventual nominee will have some persuading to do within the party as well as without. A potentially greater threat than crossover voting is that disaffected Democrats might simply sit out the general election.
Another gauge underscores the point: Just 61 percent of Obama supporters say they'd definitely or probably vote for Clinton if she wins the nomination; 38 percent say they definitely or probably would not. It's very similar among Clinton supporters: Sixty-one percent say they'd be inclined to vote for Obama, 35 percent definitely or probably not.
Among core Democrats -- excluding Democratic-leaning independents -- about a third on each side say they're disinclined to kiss and make up.
That would be a highly unusual -- perhaps unprecedented -- level of party defections. From 1992-2004 just 10 or 11 percent of Democrats have voted Republican. In 1988 Mike Dukakis yielded 17 percent of Democrats; in 1980 and 1984, Ronald Reagan attracted a quarter of Democrats.
Any significant defections of disenchanted Democrats to McCain would be a concern to the Democratic nominee. It's a balance worth watching -- but one that will be more meaningfully measured after the Democrats pick their candidate and lick their wounds.
There's also the possibility of GOP crossover: Fourteen percent of Republicans say they'd vote for Obama if he's the nominee; fewer, 7 percent, say they'd cross over for Clinton.