Lots of Democrats love. Yet plenty of Republicans, conservatives and all-important independents can't stand her, suggesting possible pitfalls for should he make her his vice presidential running mate.
The intense dislike for Clinton suggests that besides support from women and others she could bring to the ticket, she might make it harder for Obama to win over some independents, a pivotal swing group in the November election against Republican. It also means she might push some Republicans and conservatives to vote against the Democrats - or donate money to the GOP - who might otherwise lack motivation to do so because of tepid feelings toward McCain.
A substantial 32 percent of independents strongly dislike Clinton, 10 points more than say so about Obama, according to an Associated Press-Yahoo News poll. Independents, a group that both Obama and McCain won during their party primaries this year, comprised a quarter of voters in the 2004 election and have been closely contested in every presidential election since 1992.
In addition, 67 percent of Republicans have very unfavorable views of Clinton, 24 percentage points more than feel that way about Obama. Among conservatives the spread is similar - 58 percent say they feel very negatively about her, 18 points more than say so about Obama.
Few conservatives and Republicans are going to vote under any circumstances for Obama, the Illinois senator who clinched the Democratic presidential nomination last week and already has advisers culling possible running mates. But both parties will be trying to discern whether putting Clinton on the ticket might in some ways backfire.
"I don't think I'd like the idea of Hillary Clinton attached to anything," said Kym Williams, 33, of Knoxville, Tenn., a Republican who's not decided how to vote in November. "I'm not for a lot of the things she stands for."
Other groups with significantly stronger negative feelings about Clinton than Obama include whites under age 30, male college graduates, white men and whites earning at least $100,000 a year.
On the other hand, Clinton is popular with other voters, which could make her an asset to Obama. According to the AP-Yahoo survey, the New York senator is viewed significantly more favorably than Obama by many white Democrats, Hispanics and Catholics. She carried all those groups decisively against Obama in this year's Democratic primaries, exit polls of voters showed.
The AP-Yahoo poll shows little difference in how favorably the two are viewed by several other groups Clinton won during the primaries, including working-class whites, people over age 65 and women.
A comparison in the AP-Yahoo survey of how the two Democrats would fare against McCain yields similar patterns in their appeal.
Clinton does 23 points better than Obama against McCain among Hispanics, 18 points better with Catholics and 14 points better with elderly whites. Obama is far stronger among blacks, the young and college graduates.
While Clinton has told fellow Democrats she'd be open to being the vice presidential candidate, Obama has said he will take some time to decide.
Republican pollster Whit Ayres guessed Clinton would hurt Obama, but said he doubted she would have much impact drawing voters to the polls to oppose the Democratic ticket.
"Obama is plenty energizing enough for Republicans and conservatives," he said.
History shows that vice presidential nominees don't always work out as planned.
Gallup polls showed that when Rep. Geraldine Ferraro became the first female major party vice presidential candidate in 1984, over half said she made them likelier to back the party's ticket, headed by Walter Mondale. By October, after much of the campaign ended up focusing on questions about her husband's taxes, more people said her presence made them likelier to vote against Mondale than for him.
Four years later, public reaction was initially mixed when George H.W. Bush picked little known Sen. Dan Quayle of Indiana as his GOP running mate. Opinion turned negative within a month, after his Vietnam-era service in the National Guard was challenged.
Bob Beckel, Mondale's campaign manager, said Ferraro had little impact on a race Mondale lost badly to President Reagan. He said Clinton might prompt some people to vote against Obama, but mostly in GOP-dominated states Democrats would likely lose anyway.
"Mostly you don't vote for vice president, you vote for president," Beckel said.
For now, there is no definitive answer whether Clinton would help or hurt Democrats. Gallup and CNN polls last week showed the Democratic ticket doing slightly better against McCain with Clinton on Obama's ticket than when Obama and McCain were paired without running mates.
Polls do make clear how divided Democrats are over adding Clinton to the ticket. Half or more Democrats liked the idea in recent polls, but Obama's supporters are less enthusiastic than hers.
By Alan Fram