Obama’s string of strident attacks — delivered without mentioning Trump by name — is unprecedented for the wife of a sitting president, presidential historians and political strategists say.

Obama, campaigning for Hillary Clinton, painted the Republican running to succeed her husband in the White House as a short-tempered tax cheat and misogynist who “traffics in prejudice, fear, and lies.”

WASHINGTON — At an appearance in North Carolina this week, Michelle Obama had the crowd roaring with four taps of her mic — wordlessly poking fun at Donald Trump’s complaints about a faulty microphone during the first presidential debate.

Wives of presidents typically stay out of the political fray, highlighting unassailable pet causes like supporting military families but avoiding political attacks. Not Obama, who has used her status as one of the nation’s most popular political figures as an effective surrogate for the first female presidential contender.


“She’s willing to defy norms,” said Katie Packer, a Republican operative who opposes Trump. “They’re probably willing to push the envelope a little bit because this is a year where a lot of the old rules don’t apply.”

Michelle Obama’s speech to 6,000 people in Raleigh on Tuesday drew four times as many people as Clinton herself did there last week. It marked Obama’s fifth swing state appearance since her primetime address at the Democratic National Convention in July. Expect to see more of her on the trail.

It is part of a remarkable shift for a once-reluctant campaigner. She now stars in a television ad airing in Florida, North Carolina, Ohio, and Pennsylvania. In the spot, she describes Clinton as “a president our kids can look up to.”

None of Michelle Obama’s predecessors has supported her husband’s chosen successor in such an overt way, said Carl Sferrazza Anthony, historian for the National First Ladies’ Library who’s written several books about their role and their political power.


“This is the first time you have an incumbent first lady really take on a partisan role outside of reelecting her husband for a second term,” Anthony said. “Most of them prefer to remain above the partisanship.”

The last sitting president’s wife to make a campaign appearance for a presidential candidate besides her husband was Lady Bird Johnson in 1968, Anthony said. At the time, Johnson posed for photos and greeted volunteers at Vice President Hubert Humphrey’s campaign headquarters.

In contrast to Obama, Laura Bush simply made a joint appearance with Cindy McCain at the 2008 Republican National Convention. “That was as close an endorsement by a presidential spouse for a successor,” Anthony said.

Clinton, in Bill Clinton’s last year in office, spoke on Al Gore’s behalf at the 2000 Democratic convention, but her appearance provided another political benefit: She was also running for US Senate.

Obama, famously caricatured on a 2008 New Yorker cover as a gun-toting militant fist-bumping her husband, has evolved during her White House years into a pop culture icon, in part due to her appearances on daytime and late-night talk shows.

“People not that interested in politics will listen to Michelle Obama because she’s so well-liked,” Anthony said.

She’s simultaneously hip, singing “Carpool Karaoke” with Missy Elliott — and accessible, photographed shopping at Target. And she’s packaged her message of exercise and nutrition into must-watch public service announcements, including one of her slam dunking on basketball player LeBron James to promote healthy eating.


Anthony likened Obama’s many talk show appearances to Betty Ford guest starring in a 1976 episode of “The Mary Tyler Moore Show.” (Ford was also photographed performing the disco “Bump” as gamely as Obama danced the “Dougie” and did “mom dancing” on “The Tonight Show with Jimmy Fallon.”)

Deploying Michelle Obama on the campaign trail is a sound strategy for Democrats hoping to ensure President Obama’s legacy.

“She’s much more popular than Hillary Clinton throughout the country,” said Jim Manley, a veteran Democratic strategist and former spokesman for Senate minority leader Harry Reid. “And as the first lady demonstrated in North Carolina, she knows how to throw a zinger. When she wants to go for the jugular, she can.”

Obama enjoys sky-high approval ratings of 64 percent, according to a Gallup poll in August — much higher than Clinton and even the president himself.

Obama holds a unique appeal with millennials, African-Americans, and suburban women — demographic groups Clinton needs to win but whose enthusiasm she has struggled to earn, Packer said.

She also touched hearts across party lines recently when she was photographed with her arms wrapped around fomer president George W. Bush during the dedication of the National Museum of African-American History and Culture.

While Obama often sounds the same notes in her campaign speeches for Clinton, her style of delivery — and sense of comedic timing — makes her message come across as unscripted when she cautions swing voters against staying home out of frustration or protest.


“She can say things that a more seasoned politician might not feel comfortable saying,” Packer said.

Obama has more directly addressed Trump’s role in stoking the birther controversy than her husband — saying she would “certainly not” be sweeping the issue under the rug. She called Trump’s actions “hurtful” and “deceitful,” “deliberately designed to undermine my husband’s presidency.”

During the Democratic convention in Philadelphia, Obama spoke emotionally about urging her daughters to “ignore those who question their father’s citizenship or faith” and how the “hateful language they hear from public figures on TV does not represent the true spirit of this country.”

“When someone is cruel, or acts like a bully, you don’t stoop to their level,” Obama said. “No, our motto is, when they go low, we go high.”

On Tuesday in Charlotte, Obama made headlines when she praised Clinton’s resiliency, saying that when Clinton gets knocked down, “she doesn’t cry foul” — while tapping her microphone, deftly referring to Trump’s panned debate performance that he blamed on “a defective mic.”

“Don’t be fooled,” Obama said. “Preparation matters. Temperament matters. . . . Being president is nothing like reality TV — this is not an apprenticeship.”

Tracy Jan can be reached at tracy.jan@globe.com. Follow her on Twitter @TracyJan.