Vice President Mike Pence urged voters to cast ballots in Georgia's critical January runoff elections that will determine the fate of the Senate, dismissing Trump allies who asked residents this week to “not vote” until they know votes are secure.

“So between now and when the polls close on January 5, we need you to vote, Georgia," Pence said. "And we need you to tell everybody to get it done. I know we've all got our doubts about the last election. And I actually hear some people saying, just don't vote. My fellow Americans, if you don't vote, they win."

Pence spoke at a “Defend the Majority” rally Friday afternoon at the Savannah/Hilton Head International Airport --- his third appearance for GOP Sens. David Perdue and Kelly Loeffler in their closely watched runoff elections against Democratic opponents Rafael Warnock and Jon Ossoff.

With more detail than usual, Pence walked supporters through the process of how they can request an absentee ballot and reassured voters that drop boxes will be secure and they’d be “on them this time,” alluding to unsubstantiated claims of fraudulent mail-in ballots.

-ABC News' Justin Gomez

Former President Barack Obama headlined a virtual rally Friday for Georgia Democratic Senate candidates Jon Ossoff and Raphael Warnock ahead of the state's Jan. 5 runoff elections -- races that will decide the balance in the Senate.

“This is not just about Georgia, this is about American and this is about the world," Obama said.

"[Georgia is] now, once again, the center of our civic universe because the special election in Georgia is going to determine ultimately the course of the Biden presidency and whether Joe Biden and Kamala Harris can deliver legislatively all the commitments that they've made," he added.

Obama spoke at the virtual rally the same day Vice President Mike Pence traveled to Georgia to campaign for Ossoff and Warnock's Republican opponents, Sens. David Perdue and Kelly Loeffler.

Trump is scheduled to hold a rally for both candidates in the state on Saturday -- his first since losing the election.

Taking questions after his remarks on the reeling economy amid the worsening pandemic, Biden shed some light on what his inauguration might look like, distancing himself from the president's approach of flouting coronavirus guidelines and holding mass gatherings, and teasing a virtual element to the toned-down event.

"There probably will not be a gigantic inaugural parade down Pennsylvania Avenue," Biden said. "My guess is you'll see a lot of virtual activity in states all across America engaging even more people than before. But that's in training now. And I'm not in a position to give you an example of exactly what it will look like."

Asked if he believes coronavirus vaccines should be mandatory, Biden said no and added that he doesn't think mask-wearing should be mandatory either but that he'll use his position to push people toward both.

"I wouldn't demand it [vaccination] be mandatory, but I would do everything in my power -- just like i don't think masks have to be made mandatory nationwide --  I'll do everything in my power as president of the United States to encourage people to do the right thing and when they do it, demonstrate that it matters," Biden said.

Biden did say more needs to be done when it comes to vaccine distribution, saying there was "no detailed plan" his team has seen on how to physically get people vaccinated from the Trump administration.

"But there is no detailed plan, that we've seen, anyway, as to how you get the vaccine out of a container, into an injection syringe into somebody's arm. And it's going to be very difficult for that to be done and it's a very expensive proposition," Biden said.

Reiterating that he will call on Americans to commit to wearing a mask for 100 days in his inaugural speech, Biden said he expects if people follow the practice while the vaccine is being distributed they'll see deaths declining and be encouraged on their own.

"This is not a political issue," Biden said. "My hope is they'll be then inclined to say, OK, it's worth the patriotic duty to go ahead and protect other people."

Biden has previously said he would mandate masks on federal properties, a point his transition advisers confirmed in a briefing Friday morning.

-ABC News' Molly Nagle, John Verhovek and Averi Harper

Biden is poised to nominate Dr. Vivek Murthy to serve as surgeon general, a key role in the government's coronavirus response, multiple sources told ABC News. He will be elevating Murthy, a key member of his coronavirus advisory team, to the position he previously held in the Obama administration, according to the sources familiar with his plans.

Biden will begin rolling out members of his health team early next week, though a transition spokesperson declined to comment on Biden's plan's for Murthy.

Murthy, who has advised Biden on the pandemic throughout his campaign and transition, is expected to hold a broader portfolio in the next administration than he held under President Barack Obama.

Biden could also give Murthy an expanded title or elevate the role of the surgeon general within the administration, according to sources close to the transition, though no decision has been made.

Murthy is reportedly no longer under consideration to lead the Department of Health and Human Services.

Jeffrey Zients, a senior transition official who served as a senior economic adviser to Obama, is also expected to coordinate the Biden administration's coronavirus response from the White House, working with Murthy to lead the effort, according to sources close to the transition.

Additionally, Biden has asked Dr. Anthony Fauci, the nation's top infectious disease expert, to serve as his chief medical adviser.

-ABC News' Benjamin Siegel, John Santucci, Katherine Faulders, Molly Nagle and Anne Flaherty