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WATCH: Your questions about the Georgia Senate runoffs, answered

Balance of power in the U.S. Senate comes down to two runoff races in Georgia where the incumbent, now former Republican Sen. David Perdue, is being challenged by Democrat Jon Ossoff, and Republican Sen. Kelly Loeffler, who was appointed to her position after Sen. Johnny Isakson retired, is up against Democratic challenger Raphael Warnock in a special election.

The outcomes of these elections will determine whether President-elect Joe Biden can enact his agenda on crucial issues ranging from the COVID-19 pandemic to climate change with the support of lawmakers.

More than three million people voted early in this year’s runoffs, far surpassing the total turnout of two million people in Georgia’s last Senate runoff, in 2008 .

Prior to 2020, Georgia had supported Republican presidential candidates every year since 1996. Biden’s surprise victory against President Donald Trump reflects an electorate that has shifted left in recent years. Still, taking control of the Senate remains a tough challenge for Democrats.

PBS NewsHour correspondent Lisa Desjardins and political reporter Daniel Bush answered questions from viewers about what’s at stake in the Georgia runoffs.

Watch the conversation in the video player above.

Why does Georgia have two runoff races in January?

In November, Georgia’s incumbent Republican Sens. Perdue and Loeffler faced challenges from Democrats Ossoff and Warnock, respectively. When none of the candidates received at least 50 percent of the vote, which is required by Georgia law in order to declare a winner, it triggered the runoffs.

These hotly contested races underscore the significance Georgia has played in the struggle for control between Democrats and Republicans.

“It’s incredibly unusual, not only to have two elections — that happens from time to time — but to have those two elections determine the fate of the Senate,” PBS NewsHour correspondent Lisa Desjardins said.

MORE: What’s at stake in the Georgia Senate runoffs

Democratic sources in Georgia have expressed confidence that they can win both races, according to reporting by the PBS NewsHour. African American support, in addition to growing Latino and Asian communities in Atlanta suburbs, allowed Biden to win the state.

“All those are signs that point to a good day for Democrats, potentially,” Bush said of the Jan. 5 elections. “Nevertheless, this is still Georgia we’re talking about, and if [Democrats] did win them both, it would be a surprise.”

Why are these runoff races so important?

Republicans and Democrats are vying for control of the Senate, which comes down to the runoff elections in Georgia. Republicans secured 50 Senate seats in the general election, so Democrats will need to win both races for a 50-50 split in the Senate. In that case, Vice President-elect Kamala Harris will have the power as president of the Senate to cast a tie-breaking vote whenever the chamber is deadlocked.

Democrats winning control of the White House, Senate and House would be “a huge deal,” Desjardins told Bush. If they have a trifecta, “[Democrats] not only can steer the agenda, but they will be able to pass at least one major piece of legislation through a process called reconciliation” that allows the Senate to expedite passing legislation without being obstructed by a filibuster.

READ MORE: More than 1.6 million have already voted in Georgia Senate runoffs, on par with early voting in general election

Among Biden’s stated top priorities are addressing the COVID-19 pandemic, climate change and criminal justice reform. But even with a majority in the Senate, passing some legislation will not be a “slam dunk,” Bush said. “The margin of error for Democrats, if they do control the Senate are very, very slim as they are in the House where Democrats lost seats in November.”

House Democrats have so far lost a dozen seats to Republicans, which will give them the chamber’s smallest majority in 20 years. Narrow majorities make every lawmaker’s vote crucial for both parties.

Will moderate lawmakers have a lot of power in the new Congress?

Whatever the outcome of Georgia’s runoff races, slim majorities in the Senate and House mean that moderate lawmakers will play a crucial role in passing legislation.

Even if Republicans win both Senate races in Georgia, with a 52-seat majority they could only afford to lose one vote. Winning moderates’ support on key legislation will be important for both parties and important for Biden in getting his agenda through the Senate.

“Moderate Republicans are going to be targeted by Joe Biden heavily to get their support because he wants to show that he’s bipartisan,” Desjardins said.

READ MORE: In battle for the Senate, Georgia organizers fight to mobilize voters of color

“[Moderates] know the cards that they hold,” she said. “The truth is that their efforts at being bipartisan moderates have won them little except for death threats and difficult elections. Here, finally to them, it could pay off.”

In addition to considering moderates, Biden will also face pressure from progressive members, who want sweeping legislation on climate change, criminal justice and health care. Desjardins said there will likely be a “honeymoon period” between lawmakers and Biden, but progressives are closely monitoring his administration hires. Sen. Bernie Sanders, I-Vt., is one who has called for more representation of “the progressive movement” in Biden’s administration.

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