Story highlights Three Democrats are taking on the strong front-runner Hillary Clinton

Louis: Experienced members of her team recognize that her aura of inevitability could be shattered

Errol Louis is the host of "Inside City Hall," a nightly political show on NY1, a New York all-news channel. The opinions expressed in this commentary are solely those of the author.

(CNN) Experienced members of Hillary Clinton's political team, especially veterans of the bruising 2008 Democratic presidential primaries and caucuses she lost to Barack Obama, know better than to scoff at the arrival of three lesser-known new candidates to the Democratic contest for president.

The recent campaign announcements of Vermont Sen. Bernie Sanders and former Maryland Gov. Martin O'Malley, along with this week's expected entry by former Rhode Island Gov. Lincoln Chafee, suggest that a lot can go wrong for Clinton before she (maybe) gets the keys to 1600 Pennsylvania Avenue.

Errol Louis

Make no mistake: all of the newcomers would gladly trade places with Clinton, who inherits and commands a political juggernaut chock full of Democratic donors, elected officials and leaders of local political machines. She is among the best-known public figures in the world, with name recognition approaching 100% and a husband who is even better known (and immensely popular among Democratic voters).

The Clintons' tangled financial dealings , while potentially costly from an ethical standpoint, also indicate a formidable fundraising ability that will provide her campaign with ample funds for television advertising, field operations and sophisticated polling.

But polls show that Clinton, while holding impressive double-digit leads over every Republican potential adversary, still has favorability ratings under 50%. She's viewed favorably by 49%, and unfavorably by 46% -- her worst numbers since April 2008. That suggests cracks in the armor, including many of the same weaknesses that Obama exploited to masterful advantage in 2008.