ATLANTA — Former President Barack Obama implored Georgia Democrats not to “tune out” politics and to “resist the temptation to give up,” as he tried to energize his party’s most loyal voters in a state that could decide control of the U.S. Senate. Speaking to a crowd of several thousand, Mr. Obama noted the many issues that may be dampening voter enthusiasm — inflation, rising crime and the war in Ukraine — making little mention that those ills have happened while his party controls Washington. But he cast the midterm elections as a fight not over policy differences, but the health of democracy. “I get why you might be worried. I understand why it might be tempting sometimes to tune out,” Mr. Obama said. “But I’m here to tell you that tuning out is not an option.” His speech, a mix of his familiar applause lines and new warnings about threats to democratic norms, aimed to boost Democratic candidates in the state even as their party has suffered low approval ratings nationwide. He presented Democrats as the best alternative to Republican lawmakers, a group that he said is “not interested in actually solving problems.” Mr. Obama was especially pointed in his criticism of Herschel Walker, a former University of Georgia football star and the Republican challenger to the state’s senator, Raphael Warnock. Mr. Walker, Mr. Obama said, is “a celebrity who wants to be a politician.” Mr. Walker’s campaign did not immediately respond to a request for comment on Mr. Obama’s remarks.Mr. Obama arrived as the campaign enters the final stretch and Democrats are desperate to fire up their base, especially Black voters who have struggled with inflation and rising crime but have been left cold by the Biden administration. His stop in College Park, outside Atlanta, was the first of five events he is planning in coming days. He is due in Michigan and Wisconsin on Saturday, then Nevada and Pennsylvania next week — all states with close Senate races. Mr. Obama, at times, acknowledged voters’ fatigue and hardly mentioned President Biden, his former vice president. “Joe is fighting for you every day. He’s got your back. He’s doing everything he can to put more money in your pockets,” he said. Georgia Democrats have pointed to sky-high early voting figures as a sign of strength heading into Election Day. Nearly 1.3 million voters have cast ballots in the state, with the strongest performances coming from older Black voters and those in the deep-blue metro Atlanta counties of Fulton and DeKalb, according to data from the secretary of state’s office.But all signs point to strong turnout on both sides, with Republican voters poised to pour into polling places on Election Day. Mr. Biden’s approval ratings remain low, standing last month at an abysmal 37 percent in an Atlanta Journal-Constitution poll. And while key portions of the Democratic base have turned out en masse, Democrats will still need to outperform with voters under 30 and women in the Atlanta suburbs to find success in November.The State of the 2022 Midterm ElectionsElection Day is Tuesday, Nov. 8.Bracing for a Red Wave: Republicans were already favored to flip the House. Now they are looking to run up the score by vying for seats in deep-blue states.Pennsylvania Senate Race: The debate performance by Lt. Gov. John Fetterman, who is still recovering from a stroke, has thrust questions of health to the center of the pivotal race and raised Democratic anxieties.G.O.P. Inflation Plans: Republicans are riding a wave of anger over inflation as they seek to recapture Congress, but few economists expect their proposals to bring down rising prices.Polling Analysis: If these poll results keep up, everything from a Democratic hold in the Senate and a narrow House majority to a total G.O.P. rout becomes imaginable, writes Nate Cohn, The Times’s chief political analyst.“I look at the early vote numbers in Georgia, and see them as certainly positive news for Democrats,” said Tom Bonier, chief executive of the Democratic polling firm TargetSmart, which is working for the Abrams campaign. “But I think it’s also something that shows the work that needs to be done.”Friday’s rally was billed as an event for Georgia’s entire Democratic ticket. But two of its candidates took center stage: Stacey Abrams, the Democratic nominee for governor who is challenging Gov. Brian Kemp, a Republican, in a rematch, and Mr. Warnock. Ms. Abrams’ campaign has been particularly focused on winning over Black men, whose votes are also vital to Mr. Warnock if he is to defeat Mr. Walker. Black voters could also make the difference elsewhere, especially in Pennsylvania, Michigan and Wisconsin, where lagging turnout from voters of color helped Donald J. Trump secure narrow victories.“I think we’re going to see Black voters step up to the plate,” said Quentin James, president and co-founder of The Collective, a political action committee devoted to electing Black Democrats. “But you can’t divorce that from the reality that the country hasn’t always stood up for Black voters.”At a Democratic event called Georgia Black Men Call to Action, audience members listened to a speech by Stacey Abrams.Gabriela Bhaskar for The New York TimesMr. Obama tried to cast the election as dire moment for the country, pointing to Republicans’ questioning of the results of the 2020 election. Democratic candidates, he said, are a bulwark against Republican candidates who are running on a platform of election denial. “If they win, there’s no telling what would happen,” he said. Jameelah Gray, 32, after voting early at Morehouse College in Atlanta. All signs point to strong turnout on both sides in Georgia.Gabriela Bhaskar for The New York TimesThe former president’s earlier forays into midterm battlegrounds were anything but resounding successes. In 2010, he crisscrossed the country trying to rally voters — especially young voters — by telling them that Republicans had driven the economy into a ditch and Democrats had pulled it out. Unimpressed, the electorate responded with what he called a “shellacking,” handing Republicans a 68-seat gain in the House, the largest since 1948, along with seven seats in the Senate and six additional governorships.In 2014, Republicans netted nine Senate seats, cementing control of Congress for Mr. Obama’s final two years in office.Out of office, however, Mr. Obama is arguably a more popular Democratic figure than the current president — or any other Democratic leader, for that matter.“There’s nostalgia for the Obama era with a lot of swing voters,” said Tim Phillips, a Republican strategist and former president of Americans for Prosperity, a conservative political organization funded by the Koch family. “I think he’s their best spokesperson.”For his part, Mr. Biden has been a low-key presence on the campaign trail, avoiding large rallies altogether. On Friday night, he spoke at a Democratic dinner in Pennsylvania, where he celebrated Democrats’ legislative wins and railed against both Republican policies and candidates. Mr. James argued that Mr. Biden’s scarcity on the campaign trail was not really about Black voters, saying Mr. Biden was even less popular with white voters. By contrast, he said, African Americans remained deeply connected to the first and only Black president, who drew the highest turnout of Black voters in history.“Obama’s going to ramp up urgency,” he said, “not just for voting but for voting early. It will be a call to action.”The political environment for Democrats is far more uncertain than it was in either of the Obama midterms. Unemployment is low and the economy is growing, but Americans are confronting the worst inflation the nation has seen in 40 years, which is driving up interest rates and clawing back any sense of income gains as the pandemic recedes.On the other hand, the Supreme Court’s repeal of abortion rights and the looming presence of Mr. Trump are energizing the Democratic base in ways that Mr. Obama did not experience in his years in office.“Presidents look better in the rear-view mirror,” said Mo Elleithee, who was a senior official at the Democratic National Committee during the drubbing the party took in 2014.With little more than a week to go, Democrats are bracing for either a significant Republican wave that hands control of both the House and Senate to the Republican Party, or a split decision, with Democrats retaining control of a tightly divided Senate and Republicans squeaking out a narrow majority in the House.Developments in key races have only heightened Democratic anxieties. Lt. Gov. John Fetterman’s halting debate performance against Dr. Mehmet Oz, a Republican, spotlighted the effect Mr. Fetterman’s stroke had had on his ability to communicate and frayed the nerves of Pennsylvania Democrats.The Republicans’ main super PAC resumed advertising on television in New Hampshire, convinced that the race between Senator Maggie Hassan and her Republican challenger, Don Bolduc, had tightened. And prognosticators moved the Arizona contest between Senator Mark Kelly and his Republican challenger, Blake Masters, back to a tossup.Senator Chuck Schumer of New York, in Syracuse on Thursday, was recorded expressing his concerns to President Biden about where Democrats stood in Senate contests.Kenny Holston for The New York TimesPerhaps most exasperating to Democrats is the Senate race in Georgia, where a second woman this week accused Mr. Walker of having paid for her to have an abortion. Mr. Walker has denied both women’s claims.Caught on a hot microphone on Thursday, Senator Chuck Schumer of New York, the majority leader, was heard telling Mr. Biden, “The state where we’re going downhill is Georgia. It’s hard to believe that they will go for Herschel Walker.” On Friday night the Walker campaign pointed to remarks the candidate made earlier in the day where he said “Unlike Raphael Warnock I’m not a politician. I’m a warrior for God.”Jessica Taylor, the Senate analyst at the nonpartisan Cook Political Report, said, “It really does feel like there is a lot of movement in these races.” She still rates control of the Senate a tossup, but, she added, “If this is a wave, you could see others swept away,” like Senator Michael Bennet, Democrat of Colorado.On the other hand, recent polling has tantalized Democrats in Iowa, where Senator Charles E. Grassley, a Republican, is seeking another six-year term at age 89; in North Carolina, where the Democratic nominee for the Senate, Cheri Beasley, remains knotted with her Republican opponent, Ted Budd; and even in Utah, where Senator Mike Lee, a Republican, is facing an unexpectedly strong challenge from an independent, the former C.I.A. officer Evan McMullin.“This is the trickiest midterm environment I’ve seen in a long time,” said Steve Israel, a former House member from New York who once headed the House Democrats’ campaign arm.Maya King reported from Atlanta and Jonathan Weisman from Chicago. More