Just 16 days before he's set to leave office, President Donald Trump will headline a rally for Sens. Kelly Loeffler and David Perdue in Dalton, Georgia.

The rally comes on Jan. 4, the night before the two sitting senators face separate Democratic opponents -- Rev. Raphael Warnock and Jon Ossoff, respectively -- in two runoffs that could determine control of the Senate. The makeup of the Senate is currently projected to be 50 Republicans and 48 Democrats and left-leaning independents. If Warnock and Ossoff win, pushing the balance to 50-50, the Democrats would control both the House and Senate, due to Kamala Harris casting the deciding vote in the upper chamber.

Dalton is in Georgia's 14th Congressional District, which makes up the northwest corner of the state and is perhaps the state's most conservative district. Its congresswoman-elect, Marjorie Taylor Greene, has supported QAnon conspiracies in the past and has fully embraced, defended and perpetuated Trump's false narrative about the election.

The 14th Congressional District is also doing the worst of the 14 districts in terms of turnout for the runoff, according to Georgia Votes, which is analyzing the secretary of state's data.

Trump made his one and only appearance in Georgia during the runoff campaign on Dec. 5, when he spent nearly two hours ticking off baseless conspiracies about the presidential election and went on a tangent about how he didn't want to come to appear at the rally.

-ABC News' Quinn Scanlan

Continuing Biden and Vice President-elect Kamala Harris' focus on the worsening coronavirus pandemic Tuesday, the transition team announced nine additional members of the White House COVID-19 response team.

The new members will help focus on the "three crucial aspects of the COVID-19 response strategy: supply chain management, vaccinations, and testing," the transition team said.

"To recover from this pandemic, we must take aggressive action to manufacture, distribute, and administer vaccines, testing, and personal protective equipment in an equitable way. These individuals are deeply qualified and will restore public trust in the pandemic response by leading with facts, science, and integrity,” Biden said in a statement announcing the new members.

-ABC News' Beatrice Peterson

Following a meeting with his COVID-19 task force, Biden delivered remarks on the state of the worsening coronavirus pandemic and slammed the Trump administration for falling behind its goal in distributing vaccines to Americans.

"As I long feared and warned, the effort to distribute and administer the vaccine is not progressing as it should," Biden said. "If it continues to move as it is now, it's going to take years, not months, to vaccinate the American people."

The president-elected noted how officials working on "Operation Warp Speed," the federal government's vaccine program, had predicted this month 20 million vaccinations by the end of the year, but with just a few days left in 2020, the Centers for Disease Control has recorded about 2.1 million Americans as having received a dose.

"This will take more time than anyone would like and more time than the promises from the Trump administration have suggested. This is going to be the greatest operational challenge we've ever faced as a nation," Biden said. "And we're going to get it done."

Biden repeated his intention to invoke the Defense Production Act to compel companies in the private sector to accelerate the production of materials needed for vaccines and testing, as well as protective gear. He also announced that his administration will launch a public education campaign to promote vaccine acceptance and equity.

"We're also going to make sure vaccines are distributed equitably, so every person who wants a vaccine can get it no matter the color of their skin or where they live. We're going to ensure vaccinations are free of charge," he said.

Biden, overall, painted a bleak picture of soaring infections and deaths in the coming weeks, acknowledging the "grim milestone" of the U.S. crossing 330,000 deaths and saying the county may not see improvement until March. He implored Americans to wear a mask and social distance in the meantime -- and called on Trump to set an example.

"It would make a huge difference for President Trump to say 'wear masks.' I hope the President will clearly and unambiguously urge all Americans to take the vaccine once it's available," he said.

After golfing in West Palm Beach, Trump lashed out at Republicans on Twitter Tuesday in response to Senate Majority Leader Mitch McConnell blocking two efforts to pass $2,000 relief checks with a unanimous vote, saying those in his party have a “death wish” for opposing the House-passed measure.

“Unless Republicans have a death wish, and it is also the right thing to do, they must approve the $2000 payments ASAP. $600 IS NOT ENOUGH! Also, get rid of Section 230 - Don’t let Big Tech steal our Country, and don’t let the Democrats steal the Presidential Election. Get tough!” Trump said on Twitter.

It’s unclear at this point how McConnell plans to proceed, but if he does intend to tie those three issues together into one bill, as he suggested he might on the Senate floor earlier Tuesday citing the president's demands, it’s unlikely to pass.

-ABC News' Elizabeth Thomas and Mariam Khan

Biden took aim at Trump in remarks following a briefing on national security and foreign policy, slamming the current administration for failing to fully cooperate with his agency review teams during the transition -- which Biden argued could leave the country vulnerable.

While commending his own agency review teams for their hard work amid a transition that was already made more challenging by COVID-19, Biden pointedly called out Department of Defense and White House Office of Budget and Management political appointees for, he said, not cooperating for a smooth transition.

"And the truth is many of the agencies that are critical to our security have incurred enormous damage. Many of them have been hollowed out in personnel, capacity and in morale," Biden added.

Later in his remarks, Biden stressed the need for cooperation during the transition, noting that it is a matter of national security to ensure there are no gaps that adversaries can seek to exploit when he takes office.

"We need full visibility into the budget planning under way at the Defense Department and other agencies in order to avoid any window of confusion or catch-up that our adversaries may try to exploit," Biden said. "Right now, we just aren't getting all the information that we need from the outgoing administration in key national security areas. It's nothing short, in my view, of irresponsibility."

Biden said other "Day One" challenges discussed in the briefing will draw on the skill sets of the Department of Homeland Security and the Federal Emergency Management Agency as they aim to "clean up the humanitarian disaster that the Trump administration has systematically created on our Southern border."

"We will institute humane and orderly responses. That means rebuilding the capacity we need to safely and quickly process asylum seekers, without creating near-term crises in the midst of this deadly pandemic," Biden said.

As he exited the stage at the Queen Theater in Wilmington, Delaware, Biden was asked if he supports the measure for $2,000 direct payments to Americans for COVID-19 relief, which the House will soon vote on. He responded with one word: "Yes."

-ABC News' Molly Nagle, Sarah Kolinovsky and Beatrice Peterson