Michelle Obama drew plenty of attention last weekend on both the international and popular culture fronts, the publicity overshadowing what may end up being the biggest bit of Washington news she’ll make this spring, as the first lady has taken her first turn of the 2014 campaign as presidential first surrogate.  

There was considerable Beltway clucking with the release of “Fed Up,” a documentary portraying the processed food and sugar industries as responsible for the childhood obesity epidemic — and Obama’s “Let’s Move” campaign as ineffectual and co-opted by those corporate interests. (A particularly cutting opening sketch on “Saturday Night Live” leveled a similar criticism.)  

Then there were global headlines from the first lady’s effort to focus attention on the kidnapping of scores of school girls in Nigeria by Islamic militants. After tweeting out a photograph of herself holding a sign that read “Bring Back Our Girls,” she decried the abductions while filling in for her husband in delivering the weekly presidential radio address.  

All that almost completely obscured how the first lady spent part of her weekend in New Orleans with Sen. Mary L. Landrieu. Days after the president unexpectedly showed up to tour Arkansas tornado damage with Sen. Mark Pryor, it was the president’s wife who was dispatched to draw television cameras to the side of another Democratic senator with very troubled prospects for re-election. Landrieu is currently no better than a tossup bet to win a fourth term in Louisiana this fall, with Rep. Bill Cassidy the most formidable of her three Republican challengers.  

The reasons for Landrieu and the first lady’s May 10 rendezvous were not officially political. And there really wasn’t much of a campaign-style vibe to either of their joint appearances. After each received an honorary degree from historically black Dillard University, Obama and Landrieu met privately with a dozen spouses of veterans and active-duty servicemembers to discuss the complexities of transitioning their families back into civilian lives. (Supporting military families and making their lives easier has been the first lady’s main cause other than promoting exercise and better nutrition for kids.)  

“I jumped at the chance to stay,” the first lady said of the senator’s invitation, before reporters were ushered from the room. “We’re all up in Washington doing a lot of interesting things hoping that what we’re doing is impacting you all on the ground, but we don’t really know until we hear from you.”  

But midterm election dynamics unavoidably infused the Mother’s Day-timed event, and it gave rise to a wave of interest in how much the highly popular Michelle Obama would be sharing campaign duties with the much-less-popular Barack Obama over the next six months.  

Her job approval has remained remarkably consistent for the past five years, at between 65 and 68 percent in a range of polls, even as his numbers have slipped significantly since his re-election and currently average just 44 percent positive. And an NBC News/Wall Street Journal poll released last week found that while Barbara Bush and Hillary Rodham Clinton share the title of most admired first lady of the past quarter-century, at 27 percent each, Michelle Obama is very close behind at 24 percent. (But the incumbent finished first among both Democrats and African-Americans.)  

Like Pryor and three other incumbent Senate Democrats, Landrieu is running in a state Obama lost in 2012 and where he’s now less popular than he is nationally. While she’s backed the president more often than the others during the 113th Congress — voting for the Democratic budget and for tighter gun controls last year, for example — she has also frequently distanced herself from Obama’s policies. Her most recent TV commercial criticizes the president in especially stark terms, declaring him “simply wrong” on energy policy .  

There was nothing close to disagreement in New Orleans; instead, the women focused on their shared interest in supporting military families and promoting educational achievement by women and African-Americans.  

Perhaps a similar formula could allow the first lady to help others in the “Red State Five” senators running this year, even if her husband keeps his distance. Kay Hagan’s path to a second term in North Carolina will rely on strong turnout by women and minorities, Mark Begich of Alaska is on the Veterans Affairs Committee and John Walsh has made his 33 years in the Montana National Guard a centerpiece of his political narrative.  

Something of a balancing act could be required. Every time Michelle Obama draws a crowd to the side of an embattled congressional Democrat, no matter the stated purpose, she will jeopardize some of the popularity that attaches to her precisely because she’s viewed as less political than her spouse. The more publicly partisan she appears to be, in other words, the more polarizing she risks becoming  

A safer course might be to focus on wooing loyal big-money contributors. That was the principal role she played before the 2010 midterms and is what she returned to Monday. While the president was in the East Room presenting awards to courageous police officers, the first lady was headlining an intimate Democratic National Committee fundraising reception across town.  

If past is prologue, her unambiguous tone would be unsuited to a college commencement or senatorial photo op — but just right for SNL parody.  

“I’m serious, write a big fat check,” she exhorted donors at the most recent event she headlined for the DNC and for which press was permitted to cover, in Los  Angeles, at the end of January. “Write the biggest check you can possibly write.”