Late last year, Ms. Cutter left her role as deputy senior adviser in the White House to move to Chicago and become one of three deputy campaign managers, overseeing policy, research and communications. In essence, Ms. Cutter has become the chief messenger for the Obama campaign, a loyal soldier who says the things the candidate can’t (or won’t) say — often on YouTube.

In a series of straight-talking videos set in front of a bustling campaign office, she rejects point by point Mr. Romney’s policies.

“All Stephanie wants is results,” said an Obama administration aide and friend of Ms. Cutter’s who is not allowed to discuss campaign issues. “She is an old-school, take-no-prisoners political operative. Losing is not tolerated.” (Ms. Cutter has earned the nickname The Ninja at campaign headquarters, since she stealthily inserts herself into battles.)

As Ms. Cutter’s role in the campaign has become more prominent, she has become a lightning rod of controversy to detractors and a skirt-suited folk hero to supporters.

Both the adoration (“Stephanie Cutter is SOOO hot,” said one online commenter) and the attacks (“Lying liar Stephanie Cutter has hissy fit,” the conservative blogger Michelle Malkin recently tweeted) directed at Ms. Cutter are often manifest in ways that a male aide, like Mr. Axelrod or Robert Gibbs, would probably never experience.

Rush Limbaugh calls Ms. Cutter “Obama’s chief campaign babe,” and she’s also been nicknamed Box Cutter for her sharp attacks. Nicolle Wallace, a White House communications director under George W. Bush, praised Ms. Cutter as “the warrior princess of this election cycle.”