Put another way: Clinton is weakest among people who are most like her.

Take, for example, the question of whether Clinton "has new ideas for the country's future." Among adults 18-39, an impressive 61 percent believe she does. But when those over 40 respond, the positive responses plunge to 49 percent. Within her own age group of people over 65, only 48 percent believe she has new ideas.

Among those who, like her, have a college degree, only 47 percent believe she has new ideas. However, among people with no degree, it's 56 percent.

An even more puzzling result involves the statement, "She understands the problems of people like you." Among people under 40, there was a 59 percent positive response. But affirmative answers among those over 40 yielded only 51 percent.

A remarkable 75 percent of people under 40 believe Clinton is "a strong leader." Yet, among Clinton's own age group the number slips by 14 percentage points. If she runs and wins, Hillary Clinton would be 70 when she takes the oath of the office.

The question regarding leadership provides similarly surprising data among those who, like Clinton, are more affluent. Those earning less than $50,000 a year, affirm her leadership by 73 percent; those with higher incomes by only 63 percent.

The Post-ABC poll does not cross-reference demographic factors, such as age, education and wealth, with party affiliation. It could be that older, wealthier Republicans account in part for the gap in Mrs. Clinton's numbers. However, in 2012, President Obama beat John McCain handily among the most educated voters as well as the most affluent. McCain's greatest strength was among middle-age males.

In her book Clinton insists she remains undecided about running. If she does seek the presidency, she'll have to work harder than might have been expected to gain support among her peers. Why are those who've known her longest and share some of her demographic traits, beyond gender, the most skeptical?

Answers may be provided in the coming days as Mrs. Clinton makes as big a media splash as modern book-promotion can provide. She'll be taking questions from all corners and on virtually all networks about "Hard Choices."

She writes, "Ultimately, what happens in 2016 should be about what kind of future Americans want for themselves and their children -- and grandchildren. I hope we choose inclusive politics and a common purpose to unleash the creativity, potential, and opportunity that makes America exceptional."

So far, those with the longest, toughest road ahead seem most willing to buy in.

(c) Peter Funt. This column was originally distributed by the Cagle Syndicate.