ATLANTA — Shauna Mosher stood in her kitchen in suburban Atlanta on a recent Saturday, sifting through a pile of mailings from the Republican Party — a greatest-hits list of attacks on the Democratic candidates in the upcoming Senate runoffs.

"Radical socialism," they warn. "American Dream destroyed." One predicts that $93 trillion would be spent on the Green New Deal.

In ordinary times, such arguments might have worked on a voter like Mosher, a 37-year-old investor and mother of three who's leaned Republican her whole life — along with many others in her upscale community about an hour from the city who have long been drawn to GOP positions.

But in November, disgusted by President Trump, Mosher broke ranks to vote for Democrat Joe Biden — and now she watches in dismay as her state's two U.S. senators, Republicans David Perdue and Kelly Loeffler, seek reelection by voicing support for the vanquished president and his baseless claims that his own defeat was the result of fraud.

"If they have the taste of Trump," she said of Perdue and Loeffler, "they're kind of poison in my mind."

For most of the past seven weeks, the cameras and conversations in Georgia’s unusual dual Senate runoffs, which will determine which party controls the Senate, have focused on polarized voters at the margins.

Some in the GOP have fixated on whether Trump’s die-hard supporters will turn out amid his extraordinary efforts to subvert the presidential election results, including his false claims that rigged voting machines led to his defeat here. Democrats hope that Stacey Abrams’s heralded ability to turn out the Democratic base of Blacks, Hispanics and White liberals can be replicated on behalf of would-be senators Jon Ossoff and Raphael Warnock.

Just as significant, though less talked about, is a third category of voters: tens of thousands of moderate Republicans who, like centrist suburbanites across the country, rejected Trump or stayed home in November. That group is now seen by both parties as a critical bloc in future elections, including in what is expected to be a razor-thin finish in Georgia’s Senate contests.

Control of the Senate rests in the hands of Georgia voters in the Jan. 5 runoff election that will determine two seats. (The Washington Post)

These voters do not fit the image of the MAGA-hat wearing Trump backers who attend the president’s rallies or buy into his conspiracy theories, according to party officials here. Instead, these mostly White, college-educated professionals live and work in the sprawling Atlanta area. And while they tend to be conservative on economic issues and skeptical of socialist ideas pushed by some left-wing Democrats, their distaste for Trump has left them without a clear political home — at least for now.

As a result, the Senate runoffs here are taking on even greater significance than many had anticipated. Not only will they determine whether Biden will have the votes to push his agenda through Congress, but the Jan. 5 contests are also emerging as a critical early indicator of where centrist Republicans may land in what could become a post-Trump political realignment.

“What keeps us from truly jumping ship and leaving, and just saying we are done, is, I think, that there is some hope that the party will rebuild itself,” said Carter Crenshaw, a Republican who founded a group called GOP for Joe during the 2020 election. He voted for Warnock and Ossoff in the general election, and then cast early ballots for the Democrats a few days before Christmas. “But you know, I do think that it does become more and more evident every day that I don’t think that will happen anytime soon.”

Some Republican officials in suburban Atlanta have grown frustrated as they watch their state party organization continue to build itself around the notion of a dominant rural vote. Counties in metro Atlanta are some of the fastest growing in the country, filling with a diverse demographic of people for whom traditional Republican messages are ineffective.

“You can only get 100 percent turnout in a rural county,” said Lawrence “Lane” Flynn, the chair of the DeKalb County Republican Party. “All that red ink on the map is great, but at some point you run out of people. Meanwhile, there are 10,000 people a day moving to Atlanta. All our ads are people in jeans and orange vests with shotguns and pickup trucks. That’s not going to appeal to the guy from Auburn or Georgetown who just got a job in Atlanta and a condo in Brookhaven.”

Flynn cited the 2018 campaign, when then-gubernatorial candidate Brian Kemp hoisted a shotgun and a chain saw and bragged that he had a “big truck, just in case I need to round up criminal illegals and take ’em home myself.” Kemp won his primary and narrowly defeated Abrams in the general, but Flynn said such ads don’t resonate with the many potential GOP voters who live on cul-de-sacs or commute to work in Atlanta skyscrapers.

“I like Brian Kemp, but showing his pickup truck that he’s going to round up illegals in isn’t going to work for that crowd,” Flynn said.

Because of the national stakes, a hydrant of cash has poured into the state, along with prominent politicians from both parties. Trump held a rally in southern Georgia and plans to return on the eve of the election. Vice President Pence has made a half-dozen trips to Georgia, often using Air Force Two as a prop during open-air rallies outside aircraft hangars. Biden and Vice President-elect Kamala D. Harris have also held rallies in the state, encouraging Democrats to cast ballots before getting caught up in the holidays.

All signs so far point to intense voter interest. About 2.1 million people have cast ballots since early voting began Dec. 14, according to the secretary of state’s office. And by the end, both races may top the list of the most expensive Senate contests ever. Interested parties have spent nearly half a billion dollars trying to persuade voters.

Perdue and Loeffler have both aligned themselves with Trump, even calling for the resignation of the state’s Republican secretary of state, bashing him for his handling of the election. Some Loeffler ads end with the tagline: “Kelly Loeffler, 100 percent Trump voter.

But their unwavering support for Trump could put them on shaky footing with moderates.

A Georgia Republican strategist, who spoke on the condition of anonymity because of concern about jeopardizing future job prospects, said Republicans thought many moderates would stay in the fold because of economic gains the country had made under Trump before the coronavirus pandemic. But the strategist said the party has a blind spot because it doesn’t have a lot of women or minorities in its top ranks. That homogeneity has caused the party to underestimate the animus aimed at Trump for his stances on social issues like immigration and police brutality against minorities, the strategist said.

“When you look at who’s involved in the Republican Party — in the ins-and-outs and in the decision-making and the rules, it is your more extreme people rather than the people who are professionals and who are not going to go to a rally on either side,” said the party operative. “And the powers that be decided we did not need to do outreach as long as the economy is going well and people have jobs.”

As campaigning for the runoffs has continued, Republicans have tried to paint the Democratic candidates as extremists who, if elected, would be tethered to the most liberal parts of their party.

One message that has gained traction with moderates is the argument that one party shouldn’t control the fate of the federal government, and that Loeffler and Perdue would help the Senate put a check on Biden.

“Chuck Schumer, Nancy Pelosi and Jon Ossoff want total control,” Perdue says in one ad. “They win Georgia, they’ll have it. But what does that mean for you? Illegal immigrants voting. Police defunded. Taxes sky high.”

Ossoff and Warnock have argued that their opponents are out of touch with the plight of regular people, seizing in recent days on the standoff between the president and GOP lawmakers over the economic stimulus that left the fate of much-needed aid for struggling Americans uncertain until Trump signed the measure late Sunday.

The dispute perfectly encapsulated the extent to which Georgia’s senators have been caught between the traditional Republican impulse to shrink spending and the ad hoc populism and general chaos of Trump.

Both Loeffler and Perdue voted to send $600 checks as part of the stimulus legislation, far less than Democrats sought but a compromise negotiated by Trump administration officials. But then last Tuesday, the president stunned Republicans by releasing a video that blasted millions of dollars in spending on foreign aid and other programs while calling the amount of the direct payments “a disgrace” and demanding that $2,000 go to Americans.

Democratic leaders pounced, welcoming a chance to box in Republicans and demanding that GOP leaders accept Trump’s wishes — opening up an instant line of attack in Georgia.

“David Perdue, my opponent, who opposed even the first round of $1,200 checks . . . has obstructed direct relief for the last eight months, and now decided he wanted to cut it down to 600 bucks when people can barely feed their families through no fault of their own,” Ossoff said last week on CNN.

After Loeffler said she’d consider spending more on direct payments to Americans if wasteful spending was reallocated, Warnock tweeted with a thinking-face emoji: Loeffler “supports Trump 100% of the time, why won’t she support $2,000 relief checks?”

The transformation unfolding in Atlanta’s suburbs has made matters more difficult for some local Republican elected officials who have tried to forge centrist coalitions but recently have found a decreasing appetite for moderate politics.

Nancy Jester, a centrist Republican who lost a Dekalb County commissioner’s seat to a Democrat in November, said she believes her defeat was more a reflection of political polarization than a referendum on her six years in office.

“It was very hard to overcome the head winds of just having an ‘R’ by your name,” she said. “That was certainly a liability to me in a way that it never was in previous elections. Things have polarized so much, it just sort of became a scarlet letter.”

Jester said she’s not certain of her future political plans and would not say whom she voted for in the general election or favors in the runoffs.

“I make decisions based on the person and their platform rather than purely on, party,” she said in a text message. “Over the years I have earned the votes of many of my Democratic friends and neighbors who voted for me for the same reason.”

In the runoffs, Mosher voted early and cast ballots for the Democratic candidates. She accepts that Democratic control of the United States may have a negative effect on her family’s financial situation or tax rates but believes any hit won’t cause too much damage. And she believes that Democratic control would give more Americans a larger shot at the prosperity her family has enjoyed.

Plus, she has found the Republican ads unmoving, including a recent one that claimed Democrats want to outlaw hamburgers. Largely, she said, the ads have tried to stick Democrats with a negative brand instead of saying what Republicans plan to do to improve things for her family.

“Their ads are not getting to me,” she said. “If they wanted to get to me, they would be saying something different.”

Emily Guskin in Washington contributed to this report.