NORCROSS, Ga. — The biggest applause lines in Senator Kelly Loeffler’s stump speech are not about Ms. Loeffler at all.
When the crowd is most engaged, including Thursday morning at a community pavilion in suburban Atlanta, Ms. Loeffler invokes President Trump or attacks her Democratic opponents as socialists and Marxists. Her own policy platforms are rarely mentioned.
“Are you ready to keep fighting for President Trump and show America that Georgia is a red state?” Ms. Loeffler said when she took the microphone. “We are the firewall to stopping socialism and we have to hold the line.”
Such are the themes of the closing arguments in the all-important Georgia Senate runoffs, which have reflected the partisanship and polarization of the national political environment. Ms. Loeffler and her Senate colleague, David Perdue, are seeking to motivate a conservative base that is still loyal to Mr. Trump while also clawing back some of the defectors who helped deliver Georgia to a Democratic presidential nominee for the first time since 1992.
Democrats are eager to prove that Joseph R. Biden Jr.’s victory over President Trump in Georgia was more than a fluke, and that the state is ready to embrace their party’s more progressive policy agenda, rather than anti-Trumpness alone.
But the race is also emblematic of each party’s current political messages. Jon Ossoff and the Rev. Raphael Warnock, the Democratic Senate candidates, have put forth an array of policy proposals that blend the shared priorities of the moderate center and the progressive left: passing a new Voting Rights Act, expanding Medicaid without backing a single payer system, investment in clean energy while stopping short of the Green New Deal, and criminal justice reform that does not include defunding the police.
Republicans are seeking no such calibration. Mr. Perdue, who announced on Thursday that he would quarantine after coming into contact with someone who had tested positive for the coronavirus, and Ms. Loeffler are banking that their loyalists are motivated more by what their candidates stand against than by what they stand for.
There are signs that this approach has resonated with many Republican voters. At Ms. Loeffler’s event in Norcross, and later at a New Year’s Eve concert in Gainesville, voters said their top priorities were supporting Mr. Trump and his allegations of voter fraud and beating back the perceived excesses of liberals and their candidates.
“The biggest factor for me is stopping socialism,” said Melinda Weeks, a 62-year-old voter who lives in Gwinnett County. “I don’t want to see our country become the Chinese Communist Party.”
John Wright, 64, said that he was voting for Ms. Loeffler and Mr. Perdue but that he thinks Republicans must do a better job of reaching minority voters. He cited the change in racial makeup that has continued apace in Georgia and fueled Democrats’ chances at winning statewide seats.
“Republicans need to figure out how to help these people, how to reach these people,” Mr. Wright said. “Those demographics are changing, and you can’t just pitch the American dream to people who haven’t been able to achieve the American dream.”
The statewide jockeying comes at a tumultuous time in Georgia politics, as Mr. Trump continues to upend the Senate races with his baseless accusations of voter fraud, persistent attacks on the state’s Republican governor and secretary of state, and bombastic tweets regarding the coronavirus relief package.
In the last month alone, Mr. Trump has called for Gov. Brian Kemp to resign, accused Secretary of State Brad Raffensperger of having a brother in cahoots with the Chinese government (Mr. Raffensperger does not have a brother), threatened to veto the pandemic relief package, sided with Democrats on the need for bigger stimulus checks, and claimed Georgia Republicans were “fools” who were virtually controlled by Stacey Abrams and the Democrats.
Mr. Trump is scheduled to visit northwest Georgia on Monday, just one day before Election Day. The appearance underscores the complicated relationship Republicans have with the departing president at this time, according to party operatives and members of the state Republican caucus. They need Mr. Trump to motivate the base, while he remains a source of tension that has put Mr. Perdue and Ms. Loeffler under significant pressure in the runoffs.
Trump is “delivering a sort of mixed message,” said Alan Abramowitz, a political scientist at Emory University in Atlanta. “Because if you look at the rally he held down at Valdosta, the first time he came down, he spent more time airing his own grievances over the presidential election and claiming that he was cheated out of victory than he really did supporting Loeffler or Purdue. He endorsed them, but he didn’t seem to be as concerned about those races as he was about trying to re-litigate the presidential race.”
Charles. S. Bullock III, a political-science professor at the University of Georgia, said the critical question surrounding Mr. Trump’s rally is: “Will it convince some people who have up until that point said they’re not going to vote?”
Democrats, he said, had appeared to have done a better job in getting people to the polls for early voting, which ended in some places on Thursday. “So that would be the last moment — a last chance effort to get folks who have been sitting on the sidelines,” Mr. Bullock said.
Democratic candidates spent New Year’s Eve targeting voters representing their base: young voters, minority voters in the Atlanta area, and liberal churchgoers. Mr. Ossoff was scheduled to speak at two virtual “Watch Night” services, the New Year’s Eve tradition that dates to 1862, when freed Black Americans living in Union states gathered in anticipation of the Emancipation Proclamation.
Mr. Ossoff and Mr. Warnock have several drive-in rallies scheduled from Friday through Election Day, including separate events with Mr. Biden and Vice President-elect Kamala Harris.
More than three million residents have already cast a ballot in the races. The breakdown of votes so far has buoyed Democratic hopes: Population centers such as Fulton and DeKalb Counties in metropolitan Atlanta are posting sky-high turnout numbers, and the percentage of Black voters continues to trend above presidential election levels.
Videos of nearly four-hour-long voting lines in Cobb County angered some liberal groups and voting rights advocates who said it was a failure of state and local leadership. The N.A.A.C.P. Legal Defense and Educational Fund sent two letters to Mr. Raffensperger, the state’s lead election official, which warned that an increase of polling locations in the county was necessary to accommodate increased turnout.
Republicans believe that many of their supporters are waiting until Jan. 5 to vote in person. Across the country in November, Republicans saw big in-person voting turnout wipe away Democratic leads in states like Florida and Texas. Republicans could also be particularly keen to cast their ballots in person this time, considering the widespread fears of voter fraud that Mr. Trump has instilled in his base since his loss.
The announcement that Mr. Perdue would be temporarily off the campaign trail in the race’s final days startled some Republicans, who had been gearing up for Mr. Trump’s visit on Monday. Mr. Perdue is still hopeful that he will attend the rally with the president, according to a person familiar with the campaign, considering he has not tested positive for the virus and has multiple days to test negative in advance of the event.
Even before Thursday, when his campaign revealed the virus exposure, Mr. Perdue had done fewer public events than Ms. Loeffler or their Democratic opponents. The campaign did not provide an exact timeline for when Mr. Perdue might return to public events.
“The senator and his wife have been tested regularly throughout the campaign, and the team will continue to follow C.D.C. guidelines,” a statement read.
At the New Year’s Eve Concert in Gainesville on Thursday, organized by the two Republican senators’ campaigns, Mr. Perdue’s absence was not acknowledged. Instead, speakers used Mr. Trump’s scheduled appearance Monday as a hook: Go vote Tuesday after watching the president the day before.
Ms. Loeffler was joined by Senator Lindsey Graham of South Carolina, who emphasized that turnout in the north was crucial to overcoming Democratic enthusiasm in urban centers.
“This is the part of the state that runs up the score to neutralize Atlanta, you get that?” he said. “If Republicans win, I’m the budget chairman. If we lose Georgia, Bernie Sanders is the budget chairman.”
He left no room for subtext. A vote for Republicans in Georgia, Mr. Graham said, was a vote to ensure Democrats can get little of their agenda enacted in Washington.
“Anything that comes out of Pelosi’s House, it’ll come to the Senate and we’ll kill it dead,” he said, as the crowd roared with approval.
“If you’re a conservative and that doesn’t motivate you to vote, then you’re legally dead.”