ATLANTA (NewsNation Now) — Georgia’s twin Senate runoff campaigns showcase the starkly different approaches the two parties are taking to the unusual circumstances at the epicenter of a national battle for control of the Senate.

Democratic Senate hopeful Jon Ossoff is looking to unseat Republican Sen. David Perdue and Democratic Senate hopeful Raphael Warnock is facing off with Republican Sen. Kelly Loeffler.

Both sides are playing to core supporters, the most reliable voters among the 5 million who split their ballots roughly evenly between the two parties in the first round. But for Democrats, it’s seemingly a more piecemeal, voter-by-voter approach, while Republicans are pushing a broad branding message through mass media. Whichever strategy proves more effective on Jan. 5 will help determine the ambitions and reach of President-elect Joe Biden’s tenure depending on which party ultimately controls the chamber.

Republicans need one of the Georgia seats for a majority. Democrats must win both seats to yield a 50-50 Senate, with Vice President-elect Kamala Harris then holding the tie-breaking vote.

“This is literally the showdown of all showdowns,” Florida Sen. Marco Rubio told a Cobb County crowd while campaigning for Loeffler. “This is Georgia’s decision to make. But it’s America that will live with the consequences.”

Against that backdrop, the Democratic campaigns still are limiting the scope of their in-person events due to coronavirus cases rising nationally, observing social distancing and mask protocols as reflected by Biden’s presidential campaign. Meanwhile, they are ramping up voter contact and registration efforts.

Republicans counter by reflecting their presidential standard-bearer. They’re embracing unrestricted in-person events just as Trump spent the closing weeks of the presidential campaign holding his signature mass rallies in battleground states across the country — including two rallies in Georgia. And Republicans are using the events to embrace fully the nationalization of the runoffs, urging voters to see the choice as a simple one: A Senate with New York Democrat Chuck Schumer as majority leader or one with Kentucky Republican Mitch McConnell continuing in that role.

“Runoffs favor strong, well-organized campaigns,” Ossoff campaign manager Ellen Foster told The Associated Press, explaining Democrats’ tactical emphasis beyond their public events.

In the days since the runoffs were confirmed, Foster said the campaign has made “tens of thousands of calls” to existing voters while hiring new staffers focused on registering new voters ahead of the Dec. 7 registration deadline. Their targets include an estimated 23,000 young Georgians who reach the legal voting age of 18 between the Nov. 3 general election and the January runoff.

The Democratic campaign also said it has almost 22,000 volunteers scheduled for more than 60,000 hours of volunteers shifts over the next two weeks.

Republicans have an expansive campaign infrastructure to reach their voters, as well. But the opening days of the runoff campaign have been dominated publicly, at least, by sweeping attacks, from framing Ossoff and Warnock as too far left to questioning Georgia’s election process with Biden holding a narrow lead for the state’s 16 electoral votes.

Loeffler Wednesday accused Warnock of possessing “a Marxist ideology.” The Atlanta minister’s campaign spokesman Terrence Clark said the characterization was meant to “scare Georgians.” A day before, Loeffler had joined Perdue in a joint statement condemning Georgia’s vote-counting procedures an “embarrassment” and calling for their fellow Republican, Brad Raffensperger, to step down as secretary of state.

In both instances, Republicans have been short on supporting details. The goal, said former Senate candidate and U.S. Rep. Doug Collins, is to keep Republican voters “fired up.” Collins is now leading Trump’s recount effort in Georgia, though there’s no evidence that process will reverse Biden’s lead before the count is finalized and certified.

Democrats, meanwhile, hope the presidential result is a boon for runoff turnout simply because it validates party leaders’ perennial claim that Georgia is a genuine battleground state. Replicating the feat would run counter to the party’s history in recent decades, with Republicans proving more adept at maintaining enthusiasm for second-round voting.

“You know they say that we don’t show up for runoffs,” former Atlanta Mayor Shirley Franklin told Democrats this week at another Ossoff drive-in rally. “Well, we’re going to prove them wrong.”

The Associated Press writers Bill Barrow and Ben Nadler contributed to this report.