Mr. Obama does surprisingly well among evangelical Christians, an important constituency in swing states. For example, Relevant magazine, which caters to young evangelicals, asked its readers: “Who would Jesus vote for?” Mr. Obama was the winner and came out 27 percentage points ahead of Mrs. Clinton.

Politicians from red states have seemed likely to endorse Mr. Obama because many see him as the Democratic candidate who will do better in their states. Politico.com canvassed Democrats in potential swing states and concluded:

“During extensive interviews in recent weeks in Republican-leaning states, Politico found widespread belief among current and former Democratic statewide officials that Obama is the more electable candidate with their electorates. These politicians also frequently registered a fear that Clinton’s personality and past history make her too polarizing to win independent and Republican-leaning voters.”

Another way of looking at electability is to wonder whether it’s more of a disadvantage to be black or to be female. Shirley Chisholm, the black woman who ran for president in 1972, argued in effect that there were more sexists than racists in America. “I met more discrimination as a woman, than for being black,” Ms. Chisholm once said.

And recent polling and psychology research seem to back that up.

Moreover, my hunch is that a conservative woman like Margaret Thatcher may have a better chance of being elected than a feminist with a distinguished record of standing up for women’s rights. For the same reason, Mr. Obama probably has a better chance than a black candidate who emerged from the civil rights movement.

Granted, a general election campaign could shuffle judgments of electability, and it may be unwise  even offensive  to cast votes in part on how people with different political philosophies, even bigots, would cast their ballots. It’s also true that Mr. Obama has received more gentle press scrutiny than Mrs. Clinton, and if he were the nominee, he would be buffeted, investigated and swift-boated in a way that he hasn’t been (but that Mrs. Clinton has).

Then again, voters in many states have only just begun to be acquainted with Mr. Obama, and more familiarity may breed more comfort  and dispel some of the savage myths about him, such as the one claiming that he is a Muslim who doesn’t pledge allegiance to the American flag. Such lies will become harder to sustain.

Moreover, Mr. Obama’s charisma has stood up surprisingly well since he first sprang upon the stage in 2004. Some old hands believe that if he casts a spell upon many voters in red states, it’s not because of some momentary dazzle, but because he truly possesses an exceptional and enduring political talent for connecting with independent voters.

“I’ve worked for three presidents and known two or three others,” said Michael Blumenthal, who started his public career under President Kennedy and served as Treasury secretary under President Carter. “And Obama is just about the only politician I’ve ever seen who compares to Jack Kennedy.”