Is Michelle Obama the Democrats' secret weapon?

Michelle Obama has been campaigning hard in recent days, in case you haven’t noticed. Last week, chanting supporters waited hours in late-summer heat for a chance to hear her speak at a high school in Milwaukee. Then she flew to Indiana for a big event at Lucas Oil Stadium in Indianapolis. Once there, she suffered an affliction common after a long day on the stump – a glitch in her space/time continuum.

“It is just so wonderful to be here and to see all of you this afternoon, evening – what time of day is it? I’ve lost track of time,” she said. The audience laughed in response.

Then there’s her constant presence in nonhard news media. She was on Jay Leno’s “Tonight Show” two weeks ago and is set to appear on David Letterman’s “Late Show” this Wednesday to discuss back-to-school issues. (Gee, that’s right in the middle of the Republican National Convention. Do you think that’s on purpose?)

This week she’s taping a “Dr. Oz” appearance for broadcast in September. She’s been all over iVillage, a women-oriented website where she has served as guest editor, talking about everything from whether she believes women can have it all to a recent present she’s received from her hubby: gardening gloves.

Does the Democratic Party consider the first lady a secret weapon in its attempt to keep control of the White House? Maybe. If nothing else, we think there’s a good chance her husband’s campaign considers her one of its most important means of reaching out to independent voters.

Why? Well, for one thing she’s very popular. First ladies generally are – Laura Bush had high favorability ratings, too. In a Gallup poll from May, 66 percent of respondents said they had a favorable opinion of Mrs. Obama, as opposed to 52 percent who felt that way about President Obama. (His numbers have slipped below 50 percent since then.)

Plus, she’s popular with more than core Democratic voters. A Pew Research Center survey from January found that 61 percent of independents had a favorable view of the first lady. Moderate and liberal Republicans shared this view. Such voters viewed Mrs. Obama favorably by a margin of 62 percent to 25 percent, according to Pew.

And here’s the kicker: Her causes may reflect current public opinion. She’s well known for the White House garden, her Let’s Move campaign to get kids exercising, pushing healthy eating, and so forth. She’s fighting obesity – and that’s a public health problem the public at large now ranks as a major concern.

In a July Gallup poll, 81 percent of respondents judged that obesity is an “extremely” or “very serious” problem. That’s up significantly from the last time Gallup asked that question in 2005. According to this survey, Americans now view obesity as a bigger problem than smoking.

“First lady Michelle Obama’s high-profile nationwide anti-childhood obesity campaign, launched in 2010, may have ... affected Americans’ perceptions of the severity of the issue,” wrote Gallup’s Elizabeth Mendes last month.

In this context it’s easy to say why the first lady’s appearances, in which she talks about her own middle-class upbringing, the difficulties of raising Malia and Sasha, and so forth, perhaps humanize the president while reaching out to voters otherwise disenchanted with his policies.

But there are limits to how far this approach might go. It’s true that first ladies generally have high approval ratings, but those can drop if the public perceives their actions as overtly political. Hillary Rodham Clinton was a rare first lady whose favorability ratings dipped below those of her husband, in part due to her role in designing President Clinton’s failed attempt to reform health care.

And many in the GOP disapprove of Mrs. Obama's public campaigns, considering them the sort of nanny-state lecturing that defines unnecessary big government. Pew found that conservative Republicans had an unfavorable view of her, by 46 to 44 percent. Rush Limbaugh and other conservatives criticized her this month after she chided Olympic gymnast Gabby Douglas for eating a fast-food breakfast in celebration of a gold medal triumph.

“An Egg McMuffin is some kind of transgression that needs to be called out?” said Mr. Limbaugh on his show.