Hillary Clinton has bitter firsthand knowledge of just how quickly the presumed establishment favourite can stumble, fall and fail.
She's done it – eight years ago in the Iowa primary where she was trounced by Barack Obama, a younger man with a funny name who captivated Democrats with the promise of hope and change, and who erased Ms. Clinton's presumed claim on the party's nomination.
This year, with the crucial Iowa primary less than a month away and in circumstances much changed, the former first lady has a vastly better chance of winning the Democratic nomination and, perhaps, the White House.
Instead of a crowded Democratic field and a younger, charismatic main rival, Ms. Clinton faces Senator Bernie Sanders, an older candidate and a self-proclaimed socialist, and Martin O'Malley, a little-known former Maryland governor. Neither has attacked her on the issue of integrity, which will be front-and-centre if, as is widely expected, she faces the Republican presidential nominee later this year.
After losing Iowa in 2008, Ms. Clinton fought back valiantly – she won the New Hampshire primary a week later – but the superior aura of inevitability was fatally shattered in Iowa and Democrats soundly rejected her core message, that she, as a former first lady, was better placed to deliver "hope and change" than the former community organizer from Chicago.
Ms. Clinton's juggernaut campaign has more money, more staff, more organizers in more states, more endorsements from party heavyweights and more celebrity supporters than Mr. Sanders's insurgency with its legions of small-money backers and youthful enthusiasts. Money matters and more than $112-million (U.S.) poured into the Clinton coffers last year.
Even daughter Chelsea has been enlisted to seek money. "My mom will be the strongest fighter for women the White House has ever seen … chip in $1 right now to become a founding donor of Women for Hillary," was a typical recent e-mailed entreaty.
With a huge war chest, unmatched name recognition, a vast network of paid and volunteer staff in dozens of states, Ms. Clinton is the overwhelming favourite for the Democratic nomination.
And the Clintons are taking fewer chances. At all costs they want to avoid a repeat of the Iowa disaster of 2008.
Ms. Clinton is sending the man she calls her "not-so-secret weapon" – former president Bill Clinton, a formidable campaigner – out on the hustings.
In 2008, he was deployed as the "attack dog" against Mr. Obama – a role that backfired. Now, Mr. Clinton, a grandfather, is projecting himself as a champion of women's rights. And he never fails to remind Americans that he, too, will be headed back to the White House if his wife is elected president.
"I want to talk about one barrier that has not been broken," the two-term former president has joked. "I want you to support Hillary for me, too. I want to break a ceiling. I'm tired of the stranglehold that women have had on the job of presidential spouse." The underlying message is no different than it was in 1992 when the saxophone-playing, upstart Arkansas governor represented generational change.
Then, he told voters that if they backed him they would also get a tag-team presidency. "Two for the price of one," Mr. Clinton boasted of his talented wife when he was seeking the White House in 1992. There's no campaign talk this time of a "co-presidency," but if Ms. Clinton is elected as the first female U.S. president it will also be the first time a former president has returned to the White House as first spouse and Mr. Clinton's role will be unprecedented.
Both Clintons will be in Iowa, where the caucuses take place Feb. 1, and New Hampshire, which holds its primary Feb. 9, more or less constantly over the next month.
As for Mr. Sanders, his populist message, rumpled appearance and avuncular style have stopped Ms. Clinton's run for the Democratic nomination from turning into a coronation parade.
But he remains an outsider. In recent Iowa polls, Mr. Sanders trails Ms. Clinton by an average of 15 points. He frankly admits that without an unprecedented turnout among the young – the group least likely to gather for a long evening of caucusing in frigid Iowa, his hopes are dim. "If the voter turnout is low, we probably will not win," Mr. Sanders said in December.
Ms. Clinton is already telling Sanders supporters that she admires their devotion to his populism but expects their support once she beats him. "I respect anyone who is supporting one of my Democratic opponents, but I would just ask, once this nomination is wrapped up, that they come and join with us to make sure that we don't turn the White House back over to the Republicans," she said.
Mr. Sanders, a senator from Vermont, is pinning his hopes on a win in New Hampshire, the second state on the long primary calendar. It's his next-door state and most polls currently show him ahead of Ms. Clinton.
But other than New Hampshire, Mr. Sanders's hopes look bleak.
Meanwhile, the third Democratic candidate still running, Mr. O'Malley, is so far behind – polling less than 5 per cent in national polls as well as in Iowa and New Hampshire – that it may be only a question of time before he throws in the towel.