Hillary Clinton will enter the 2016 presidential race with the strongest chance to win the White House of any non-incumbent front-runner in decades, from either party. That doesn't mean she will win.
Her current strength within her own party is overwhelming. The most recent NBC News/Wall Street Journal poll showed that virtually all Democratic primary voters were willing to vote for her. She may have Democratic primary rivals, such as former Maryland Gov. Martin O'Malley or Vermont Sen. Bernie Sanders. None has the star power Barack Obama had when he upset her for the 2008 nomination.
Clinton herself lost out to Obama's star power in 2008. Yet her campaign will gain a charge of electricity from the possibility of America's first woman president, just as Obama's did for shattering racial barriers to the Oval Office.
Read More Hillary Clinton to Announce Presidential Bid As Early As Sunday
She benefits from largely positive memories for her husband's presidency during the 1990s economic boom. She established an independent political identity as senator from New York, and then through loyal service to her one-time rival as President Obama's Secretary of State.
Clinton also stands to benefit from cultural and demographic shifts that, absent extraordinary circumstances, have left Democrats with a standing electoral advantage in presidential years. The Republican Party remains dependent on overwhelming support from white voters. But that base has inexorably shrunk in recent decades, from 88 percent of the electorate in 1980 to 72 percent in 2012.
Democrats dominate the swelling non-white vote. And their party's tolerant stance on cultural issues such as gay rights more closely match the sentiments of a diverse and evolving nation than those of the GOP, in which conservative Christians remain a powerful force.
Read MoreSen. Ted Cruz blames the media for distorting his image
Clinton faces significant challenges nonetheless.
The soaring poll ratings she enjoyed as Secretary of State have already begun to taper as she's viewed through the partisan lens of a presidential candidacy. They'll fade further once she begins actively campaigning and detailing her social, economic and foreign policy agenda.
Her identification with her husband's presidency, though it confers some advantages, also ties her to the past. At age 67, she could find herself on the wrong side of a debate about leadership for the future if Republicans nominate on their younger contenders such as Sen. Marco Rubio or Gov. Scott Walker. O'Malley may test drive that argument in Democratic primaries, even if lacks the capacity to win the nomination.
Former Florida Gov. Jeb Bush, though he has significant vulnerabilities of his own, is campaigning in a style that could modernize and expand the aging Republican electoral coalition. He is seeking to project greater pragmatism and optimism than his Republican rivals.
Read More Read MoreGov. Jindal: 'Maybe I'm not what they think a conservative should look like'
Perhaps most importantly, his fluent Spanish, marriage to Mexican-born Columba Bush, experience leading Florida's diverse constituency, and openness to comprehensive immigration reform opens the door to increasing support from Hispanic voters. In a country that remains polarizing and closely divided along partisan lines, Clinton's campaign team acknowledges that Bush has the capacity to defeat her.
Her own performance on the campaign trail, of course, will also influence the outcome. She lacks the relaxed, fluid campaign style her husband has always displayed, as well as Obama's soaring speech making ability. She displays suspicion and impatience with the media that will now track her every step and utterance.
As veteran Democratic lobbyist Paul Equale put it on Twitter: "Her biggest problem is beating herself."