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 reelection 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 favorability rating at 66 percent in May, better than the president's current Gallup approval level of 45 percent.

"One of the big differences between 2008 and 2012 is that the president now has a record, and his favorability ratings have declined," said Brian Frederick of Bridgewater State University.

"She hasn't suffered in the same way to any great degree over the last four years, so it's helpful for the president to have a more popular surrogate.

"The campaign is well aware of that and they want to exploit it as much as possible," said Frederick, who has studied the political impact of political spouses on the fortunes of presidential candidates.

In America and abroad, Michelle Obama has a common touch that sometimes evades her husband as when dancing with children at a school in India, and befriending black girls from inner city London.

Obama also flew the flag, and was photographed hugging US athletes, at the Olympics.

While eschewing partisan combat, Obama's rhetoric appears to be driving a sharp implicit comparison between the president and a wealthy opponent who rarely talks about his past.

"We all know who my husband is, don't we?" she said in Dubuque.

"We all know what he stands for.

"What I remind people is that your president knows what it means when a family struggles. This is not a hypothetical situation for him."

Michelle Obama was not always as politically dexterous, and once was a more polarizing figure.

She unleashed a torrent of criticism in the 2008 campaign, when, in noting exploding support for her husband, she said: "for the first time in my adult lifetime, I am really proud of my country."

Her time as first lady has also seen missteps, including a lavish trip to Spain in 2010 panned by critics and mocked by conservative radio talk show hosts as evidence of undue entitlement.

Obama has refashioned her image carefully, stressing her humble upbringing and her life with daughters Malia and Sasha rather than her professional and academic pedigree with degrees from the universities of Harvard and Princeton.

And she insists she has no desire to follow a recent predecessor, Hillary Clinton, into politics in her own right.