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.
As noted, there are other concerns for Democrats -- the level of Democratic partisanship, and also whether Republican allegiance will recover. On average across 2007 just 25 percent of Americans identified themselves as Republicans, the lowest percentage since 1984. So far this year it's ticked up to 28 percent on average; in this poll, 29 percent.
NOVEMBER – As things stand, this poll suggests a close general election contest. Obama has a scant 5-point advantage over McCain, 49-44 percent, compared with a 52-40 percent race last month. McCain and Clinton stand at 48-45 percent; it was a Clinton advantage, 50-44 percent, last month.
One factor is the shift in partisan affiliation. Another, in the McCain-Clinton matchup, is independents, one of the key swing voter groups. Last month, Clinton had a 7-point edge among independents; now it's a 10-point McCain advantage. (Obama continues to lead McCain among independents, by 8 points.)
All the candidates have vulnerabilities. McCain's major speech on the economy this week was likely aimed at his comparative weakness in this area; among voters who say the economy is their top concern he trails Obama (by 53-39 percent) and Clinton (by 51-42 percent) alike. And the economy is the top issue by far, cited by 41 percent; the war in Iraq follows, cited by 18 percent as their chief concern.
In another measure, Americans by 55-34 percent say a Democratic president would do a better job than a Republican handling the economy; and by 52-35 percent also believe a Democrat would do a better job dealing with the situation in Iraq.
McCain's age -- he'd be the first president to take office at 72 -- is also a continued negative; 26 percent say it makes them "less enthusiastic" about supporting his candidacy, including 13 percent of Republicans and 24 percent of independents. That is, however, down slightly from its high, 31 percent in January.
Nearly half of Americans, 48 percent, also think McCain's temperament would hurt his ability to serve effectively as president. But 51 percent say Obama's level of experience would hurt him, and 49 percent say Clinton would be damaged by her political style. Each is a broad enough concern for the candidates to take notice.
FAVORABILITY – Clinton and Obama are not alone in their higher unfavorability ratings. McCain's unfavorable score, similarly, has gained 10 points since January, to 40 percent; and Bill Clinton's has advanced about as much, to 51 percent, its worst since he left office.
Both Clintons stand out in the level of antipathy they attract. Thirty-nine percent of Americans have a "strongly" unfavorable opinion of Hillary Clinton (up 10 points since January); fewer, 22 percent, have a "strongly" favorable view (down 10 points). Thirty-four percent are strongly negative on Bill Clinton.
ATTRIBUTES – Hillary Clinton, naturally, does much better on favorability in her own party (29 percent unfavorable among leaned Democrats versus Obama's 21 percent). But she's got trouble versus Obama on several specific personal attributes, which matter especially in primaries, with candidates relatively close on the issues.