ATLANTA — Sky-high turnout among Black voters powered a pair of Democrats to Senate victories in Georgia, reshaping the balance of power in Washington as President-elect Joe Biden takes office.

More than 4.5 million Georgians voted in the January runoff elections, shattering previous records and rivaling the turnout in November, when the state elected a Democrat for president for the first time since 1992.

This extraordinary level of enthusiasm reflected the high-stakes nature of the contest, which determined control of the Senate and Biden’s ability to pursue an ambitious Democratic agenda.

But voters say the victories of Jon Ossoff and Raphael Warnock also highlight the important role Black Georgians play in Democratic politics, and the growing sway they’ll have on the party in the future.

“I am full of joy and gratitude for all the Black voters in Georgia, because they are the reason we have this victory,” said Wanda Mosley, senior state coordinator for Black Voters Matter.

Mosley and others credited the win to a years-long effort to register and engage Black voters who infrequently, or have never, cast a ballot.

Over the past two months, Black Voters Matter distributed hundreds of thousands of door hangers with voting instructions and information about three issues that resonate with Black Georgians: coronavirus relief, systemic racism and voting rights.

On the last day of early voting, the group hosted a “Collard Green Caucus,” serving a traditional Southern New Year’s meal of collard greens and black-eyed peas near polling places to encourage early voting.

Another group, the Clayton County Black Women’s Roundtable, a nonpartisan civic engagement group focused on Black communities, distributed food baskets for the holidays to try to make more personal appeals to voters.

“A lot of people are told that Black people don’t vote,” said Farin Robinson, 31, a recent law school graduate in Douglasville, Ga. “Black people do vote, and we turn out in big numbers.”

In fact, the share of Black Georgians in the January runoff was on par with the November election, when they played an important role in flipping the presidential vote to Biden. State data suggest that Ossoff won a greater share of Black voters from outside the liberal Atlanta metro area than he did in the November election, which can be partially credited for his narrow victory.

Activists say that the runoff victories highlight the importance of continuing to engage voters year-round, including for local elections for school boards and police departments. The key is to be a constant presence in local communities so that they gain voters’ trust and help them stay civically engaged, Mosley said.

“We are not parachuting into the ‘big elections.’ There’s no such thing as an off-year,” Mosley said. “Our model of investing in communities and organizations and leaders at the grass-roots level is why we have gained this level of respect and trust.”

Racial issues also were at the forefront of the campaigns of Raphael Warnock and Ossoff, which helped engage voters. The campaigns emphasized the disproportionate toll that the coronavirus has had on Black communities and businesses and the systemic injustices that have led to the deaths of unarmed Black men such as Ahmaud Arbery, 25, who was shot and killed while jogging in early 2020 in Glynn County, Ga.

Warnock’s ability to connect with Black voters probably also played a role. On the eve of the election, Warnock spoke to a crowd of supporters at a drive-in rally in Riverdale, a city south of Atlanta where more than 85 percent of residents are Black, and greeted them: “Welcome to the new Georgia, welcome to the blue Georgia.”

Warnock quoted Fannie Lou Hamer, the legendary civil rights leader who ran for Congress in 1964, challenging the racist White establishment and declaring she was “sick and tired of being sick and tired.”

“I’m sick and tired of having to say what we all ought to already know,” Warnock told the crowd. “So, I want you to take that frustration, take that righteous indignation, take it all the way to the polling booth.”

Drew Andrews said Warnock was one of the reasons he cast his ballot early and encouraged family, friends and neighbors to do the same.

Andrews said that Warnock’s sermons at Ebenezer Baptist Church resonated with him, and other voters he has spoken with — especially those directly affected by the coronavirus pandemic and those who marched in the summer’s protests for racial justice — felt the same.

“More people are starting to understand” long-standing racial and economic inequalities, Andrews said. “This election does feel different.”

Michael McDonald, a political science professor at the University of Florida who has closely tracked turnout, said Warnock’s candidacy contributed to the surge in the Black vote.

“The fact that Warnock was on the ballot gave extra incentive for African Americans to show up and vote and support him. And Ossoff undoubtedly benefited from some of that,” he said.

Autumn Thompson, a 21-year-old resident of Mableton, Ga., still remembers learning about the U.S. presidents in the third grade, and noticing that every single one of them was a White man. One year later, that changed with Barack Obama’s election.

Now, after casting her first-ever vote for president in the fall, Thompson returned to the polls a second time to help elect her home state’s first-ever Black senator.

“Now we feel like things that seemed impossible are possible,” she said. “Warnock becoming the first Black senator from Georgia seemed impossible. A state that was really influential in Jim Crow back in the day now has a Black senator. It’s an amazing thing to see and gives me hope for the future.”

The day after Georgians elected Warnock to the Senate, a group of his supporters visited the Ebenezer Baptist Church to mark the stunning electoral victory of its pastor.

At the church,  where Martin Luther King Jr. was once pastor, voters said they wanted to celebrate the first African American Democratic senator from a former Confederate state, who grew up in the Savannah, Ga., housing projects.

“He brings a different mind-set to the table,” said Terri Sims, 36, who visited the church with her family. “He’s been talking to the people on the streets. He’s been talking to the middle class, the lower class, he’s seen it with his own eyes, he’s tasted it, he’s smelled it, he’s lived it.”

But activists say there is more work to be done. Nsé Ufot, chief executive of the voter-mobilization group New Georgia Project, noted that while Georgia Democrats were celebrating their victory, a mob of protesters had swarmed the U.S. Capitol to challenge the election results.

“This big divide between the rhetoric of American democracy and the reality of how we experience it, we have work to do,” Ufot said. “This is not about the battle; it’s about the war.”

Vanessa Williams and Scott Clement contributed to this report.