Jill Biden’s weekend included five flights, 11 events, and three meetings with Democrats who all asked for her assistance ahead of the midterm elections. There was also a spin class somewhere in there.

During one particularly hectic 27-hour period, Dr. Biden, the first lady, appeared in Atlanta, where voting rights activist Stacey Abrams is facing an uphill battle against Republican governor Brian Kemp. Then she went to Florida, where she toured a breast cancer research facility and spoke with Newsmax, a conservative network. She then appeared alongside Representative Val B. Demings, who is running against Senator Marco Rubio, and Charlie Crist, a centrist Democrat who is trailing Ron DeSantis, the governor and conservative firebrand.

With President Biden’s job approval hovering around 40% at a time when Democrats are struggling to retain control of the House and Senate, Dr. Biden has become a lifeline for candidates seeking attention and money without the baggage that an appearance with her husband would bring. According to a senior White House official, she is the administration’s most frequently requested surrogate.

Modern first ladies are often expected to humanize or translate their husbands’ policies, but how much they choose to engage is almost always up to them. Melania Trump was more popular than her husband and was a much-requested surrogate, but she did not campaign for him during the 2018 midterms or the 2020 campaign, frequently claiming that she was too busy parenting her son or juggling her own obligations as first lady.

Michelle Obama was widely regarded as a Democratic secret weapon ahead of the 2010 midterm elections, when she campaigned with personal stories about her family. However, she spent significant time away from politics, and her popularity was insufficient to offset the Democrats’ losses in the House and Senate that year.

Women who try to do too much face the following risks: When Democrats lost their House majority in 1994, Hillary Clinton publicly apologized for her efforts to reinvent health care.

Lauren A. Wright, a Princeton professor who has written extensively about first ladies’ political appearances, said the East Wing under Dr. Biden, 71, who continued teaching as an English professor as first lady, has become completely intertwined with the West Wing’s political efforts.

Dr. Biden has visited 40 states as first lady, and she has recently tucked a slew of political visits into trips that highlight her policy interests. She taught a full day of classes at Northern Virginia Community College on Thursday before flying to Fort Benning, Georgia, to meet with military families.

Her political appearances began on Friday evening, when she stood in the foyer of a home with Ms. Abrams and invited 75 attendees, mostly women, to take a step closer to her. Then she went after Mr. Kemp and the policies he supports, such as a law he signed that prohibits abortions after about six weeks of pregnancy and another that restricts voting rights.

Her presence is more than just a morale booster for Democrats in tight races: she is a fund-raising draw who appeals to grassroots supporters, and people are more likely to donate if she asks, according to a Democratic National Committee spokeswoman who was not authorized to speak publicly. Democrats have raised millions of dollars as a result of her events, emails, text messages, and mailings.

Dr. Biden told her Atlanta audience that she knew they had already given, but “I’m asking you to dig a little deeper.” The whole thing took about 20 minutes, and then she was off to the next event, slipping out through a kitchen door with a slew of aides.

Dr. Biden was in Florida by Saturday morning, her second visit this month, and she began the day on a bike at a spin studio in Fort Lauderdale with several aides. She then had coffee with Representative Debbie Wasserman Schultz in Fort Lauderdale before touring a breast cancer research facility with her.

She spoke with the host of a Newsmax show about breast cancer awareness before flying to Orlando to join Mr. Crist and Ms. Demings in front of City Hall, clasping hands and holding their arms up in a victory gesture.