ORLANDO, Fla. — Jill Biden’s weekend included five flights, 11 events and three appearances with Democrats who all requested her help ahead of the midterm elections. There was also a spin class in there somewhere.During one particularly busy 27-hour chunk of time, Dr. Biden, the first lady, appeared in Atlanta, where the voting rights activist Stacey Abrams is in an uphill race against Brian Kemp, the Republican governor. Then it was on to Florida, where she toured a breast cancer research facility and gave an interview to Newsmax, the conservative network. After that, she appeared with Representative Val B. Demings, who hopes to unseat Senator Marco Rubio, and Charlie Crist, a centrist Democrat who trails Ron DeSantis, the governor and conservative firebrand.“It’s not going to be easy,” Dr. Biden, on the last leg of a 15-hour day, told a group of people at a second event to support Ms. Demings on Saturday. “But we know how to win because we’ve done it before.”With President Biden’s job approval hovering at about 40 percent at a moment when Democrats are struggling to hold on to the House and Senate, Dr. Biden has become a lifeline for candidates trying to draw attention and money but not the baggage that an appearance with her husband would bring. According to a senior White House official, she is the most requested surrogate in the administration.“She does not offend people in a way that a president can because she’s much less polarizing and political,” said Michael LaRosa, a communications strategist and her former press secretary. “It’s why she was sent all over rural Iowa and New Hampshire during the campaign and why she can go places now that the president can’t.”Modern first ladies are usually relied on to humanize their husbands or translate their policies, but how much they decide 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 during the 2020 campaign, often saying she was too busy parenting her son or tied up with her own engagements as first lady.Dr. Biden greeting supporters at a campaign event in Iowa in February 2020. Joshua Lott/Getty ImagesMichelle Obama was largely viewed as a secret weapon for Democrats ahead of the 2010 midterms, when she campaigned with personal stories about her family. But she spent large stretches of time away from politics, and her popularity was not able to counter the losses the Democrats sustained in the House and Senate that year.There are risks involved for women who try to do too much: When Democrats lost their House majority in 1994, enough people blamed Hillary Clinton’s efforts to reinvent health care that she publicly apologized.Lauren A. Wright, a professor at Princeton who has written extensively about political appearances by first ladies, said the East Wing under Dr. Biden, 71, who kept teaching as an English professor as first lady, has become completely intertwined with the political efforts of the West Wing.The State of the 2022 Midterm ElectionsWith the primaries over, both parties are shifting their focus to the general election on Nov. 8.The Final Stretch: With less than one month until Election Day, Republicans remain favored to take over the House, but momentum in the pitched battle for the Senate has seesawed back and forth.A Surprising Battleground: New York has emerged from a haywire redistricting cycle as perhaps the most consequential congressional battleground in the country. For Democrats, the uncertainty is particularly jarring.Arizona’s Governor’s Race: Democrats are openly expressing their alarm that Katie Hobbs, the party’s nominee for governor in the state, is fumbling a chance to defeat Kari Lake in one of the most closely watched races.Herschel Walker: The Republican Senate nominee in Georgia reportedly paid for an ex-girlfriend’s abortion, but members of his party have learned to tolerate his behavior.“This role has become so serious and political,” she said. “It must be part of the strategic White House planning and effort. Otherwise you’re wasting opportunities.”As first lady, Dr. Biden has traveled to 40 states, and lately, she has tucked a plethora of political visits into trips that spotlight her policy interests. On Thursday, she taught a full day of classes at Northern Virginia Community College before flying to Fort Benning in Georgia, where she visited with military families.Her political appearances began on Friday evening, when she stood in the foyer of a home with Ms. Abrams and asked some 75 attendees, mostly women, to step closer to her. Then she took aim at Mr. Kemp and the policies that he supports, including a law he signed that bans abortions after about six weeks of pregnancy, and another that limits voting access.“I know that makes you angry,” she told them. “And it should make you angry.”Her presence is not just a morale boost for Democrats in close races: She is a fund-raising draw who appeals to grass roots supporters, and people are more likely to donate if she’s asking, according to a spokeswoman who works for the Democratic National Committee who was not authorized to speak publicly. Her events, emails, text messages and mailings have drawn millions of dollars for Democrats.In Atlanta, Dr. Biden told her audience that she knew they had already donated, but “I’m asking you to dig a little deeper.” (Each had already paid at least $1,000 to attend the event.) The whole appearance took about 20 minutes, and then she was on the road to the next event, slipping out through a kitchen door with a coterie of aides.By Saturday morning, Dr. Biden was in Florida — her second visit there this month — where she started the day on a bike at a spin studio in Fort Lauderdale with several aides. (Aside from finding boutique fitness classes when she travels, she is also an avid runner, and has said that the exercise “creates a sense of balance in my life.”) Then she stopped for a coffee (black, no sugar) with Representative Debbie Wasserman Schultz in Fort Lauderdale before the two of them toured a breast cancer research facility.She delivered an interview focused on breast cancer awareness with the host of a show on Newsmax, then she flew to Orlando, where she appeared with Mr. Crist and Ms. Demings in front of City Hall, clasping hands and holding their arms up in a victory gesture.Dr. Biden, who recently spent time in Florida with Mr. Biden and Mr. DeSantis to tour storm damage from Hurricane Ian, offered her pointed assessment of the state government: “This state deserves a governor who will get to work for all of Florida’s families.” After the event, Dr. Biden, surrounded on all sides by Secret Service agents, walked down from the steps of City Hall and toward a group of people who wanted to shake her hand.Dr. Biden and President Biden toured storm damage in Fort Myers, Fla., with Gov. Ron DeSantis this month.Doug Mills/The New York TimesThe first lady is not the only Democrat crisscrossing the country ahead of the midterms.Transportation Secretary Pete Buttigieg, a smooth-talking Midwesterner and potential future presidential candidate is also high on the list of popular surrogates. Kamala Harris, the vice president, has an approval rating lower than the president, but she has been sent across the country to energize young voters on issues including abortion rights and student loans.Dr. Biden is used differently.The first lady has long been thought of in Biden world as a “closer”: a surrogate they rely on to travel to corners of the country that her husband cannot easily reach, ideologically or geographically. White House officials believe she appeals to suburban women and can communicate to Americans “beyond the Twitterverse and cable news chatter,” according to Elizabeth Alexander, her communications director.Compared with her husband, Dr. Biden is the more disciplined communicator. Her missteps, which are rare, have occurred not off the cuff but during the speeches she works to commit to memory. Over the summer, she was criticized when she compared the diversity of the Hispanic community to the breadth of breakfast taco options available in Texas.She is incredibly protective of Mr. Biden, and has been involved in the hiring of his press staff and other senior aides. (She vetted Jen Psaki, Mr. Biden’s first press secretary, alongside her husband.) She has been direct when she believes they have not protected him: After Mr. Biden delivered a nearly two-hour news conference in January, members of his senior staff were rehashing the appearance in the Treaty Room when the first lady appeared.She pointedly asked the group, which included the president, why nobody stepped in to stop it, according to a person who was in the room. Where was the person, she demanded, who was supposed to end the news conference?Dr. Biden after a presidential debate in 2020. She can be President Biden’s staunchest defender on the campaign trail.Hilary Swift for The New York TimesThe first lady is also Mr. Biden’s staunchest defender on the campaign trail: Within each interaction, each visit or even each naysayer, she sees an opportunity to extol her husband’s accomplishments — and maybe change someone’s mind.In event after event, people try to come close to her, for a picture or a hug or, sometimes, to air their grievances. This year, as they did on the 2020 campaign, Democrats have approached her at events to share their thoughts about the president, including suggesting that he is too old for the presidency. She replies by ticking off her husband’s accomplishments, his travel schedule and his victory over Donald J. Trump.“I’ve been to places where they think Joe is the best thing ever,” she said next to Ms. Abrams on Friday in Atlanta. “And there have been times when I’ve been met with anger or hurt. But I’ve also found that the values that united us are really deeper than our divisions.”Polling shows that Americans have mixed feelings about her. A CNN survey this summer found that some 34 percent of Americans had a favorable opinion of Dr. Biden, compared with 29 percent who said their view was unfavorable. Almost as many people — 28 percent — had no opinion, and 9 percent said they had never heard of her.That poll also found that she performed well with women and Black voters, and people from both groups turned out to see her as she went from event to event over the weekend.Dr. Biden speaking during a campaign event in Iowa in January 2020. “She does not offend people in a way that a president can because she’s much less polarizing and political,” her former press secretary said.Andrew Harnik/Associated PressIn speeches designed to warm up a crowd and draw laughs, she shared several snapshots of her life story: “When I first met Joe, I felt really kind of out of touch with his world in D.C.,” Dr. Biden said. “On our first date, I remember saying, ‘Thank God I voted for him.’”As the sun was setting in Orlando on Saturday evening, she repurposed a story that she recently shared for the first time, telling supporters that she once helped a friend recover from abortion in the late 1960s, before Roe v. Wade had established a constitutional right to an abortion. “It happened a long time ago, but it is a story that might not be unfamiliar to you,” she told Ms. Demings’s supporters.They nodded along as she spoke. More