The political emergence of Michelle Obama

• Michelle Obama is also a character witness for the man she married 20 years ago
• She has taken the intensity of her campaigning up a notch from her pace of four years ago
• Obama has largely avoided direct political combat

With charm, hidden steel and growing political skill, First Lady Michelle Obama is injecting a timely jolt of verve into her husband's battered political brand.

The price of a sluggish economic recovery weighs heavily on President Barack Obama as he wages a tough re-election fight against Republican Mitt Romney.

But the first lady, once an uncertain and reluctant political performer, is seeking to energize what will, win or lose, be her husband's last campaign.

Acting as a fundraiser, catalyzing grassroots efforts and pumping up the president's crowds, Michelle Obama is also drawing implicit, yet striking contrasts between her husband and his wealthy foe.

Obama is also a character witness for the man she married 20 years ago.

"The one thing I share with people is that over the last three and a half years, as first lady, I have had the chance to see up close and personal what being president really looks like," Obama said in Iowa on Wednesday.

"And I've seen some things," she joked.

Obama, wearing a Stars and Stripes themed red-and-white checked dress with a blue belt, described "the judgment calls where the stakes are so high and there's absolutely no margin for error," and tugged at the heartstrings of Iowans she hopes will turn to her husband again.

Her flirtatious manner also drew the president out of himself, lifting his fatigue after a three-day bus tour of the Midwestern swing state.

"Their schedules are both so busy that they don't get to campaign together that often -- they just like being around one another," said Obama spokeswoman Jen Psaki.

Campaign aides agree that Michelle Obama has taken the intensity of her campaigning up a notch from her pace of four years ago.

She has headlined 73 fundraising events since April, as her husband struggles to match Romney's multi-million-dollar money machine.

Add to that 22 political events and her leadership of an "It Takes One" initiative, designed to show supporters that even a small contribution can make a difference.

Obama often pops up on television, reaching out to young, women and African American voters -- key parts of the president's coalition -- for example when sharing a couch with Olympic gymnast Gabby Douglas on "The Tonight Show with Jay Leno."

"A fashion icon and an athletic mother of two, she's Jackie Kennedy with a law degree from Harvard and street sense from Chicago's South Side," said Forbes magazine, placing her on its 100 most powerful women list in 2010.

Obama has largely avoided direct political combat, preferring to build goodwill with healthy eating and fitness campaigns, and a drive to help families of military veterans.

As a result, she is more popular than her husband, and a political asset to boot.

Gallup pegged Michelle Obama's favourability rating at 66 percent in May, better than the president's current Gallup approval level of 45 percent.