Former astronaut and retired Navy Capt. Mark Kelly is slated to be sworn in as Arizona's second Democratic senator Wednesday afternoon, shaving the Republican’s majority by one vote for the final weeks of the lame-duck session and marking the first time the state has had two Democrats in the Senate in 67 years.

The ceremony is scheduled to begin on the Senate floor around 2 p.m. He's expected to be escorted to the dais by fellow Arizona Democrat Sen. Kyrsten Sinema where Vice President Mike Pence, as Senate president, is expected to swear Kelly in. Former Rep. Gabby Giffords, Kelly's wife and activist against gun violence, is expected to attend. After the official swearing-in, Kelly will go to the Old Senate Chamber for a photo op.

Kelly's victory over GOP Sen. Martha McSally helped narrow the Senate GOP's majority from 53-47 to 52-48. The balance of power -- and the promise of Biden passing big ticket legislation he's hoping for -- now hangs on two runoff elections in Georgia. If Democrats win both races, the Senate would be split 50-50, and incoming Vice President-elect Kamala Harris would cast tie-breaking votes in the upper chamber.

-ABC News' Trish Turner

Georgia Secretary of State Brad Raffensperger at the State Capitol in Atlanta defended Gabriel Sterling's impassioned and angered plea to Trump Tuesday and said while he may not have used the same language, he was aware of what Sterling was going to say and that he had the "full support" of the secretary and his office.

"He spoke with passion, and he spoke the truth, and it's about time that more people are out there speaking the truth," Raffensperger said.

Sterling, the state's voting system implementation manager, on Tuesday slammed Trump and GOP Sens. Kelly Loeffler and David Purdue for what he deemed their silence on failing to condemn harassment and death threats against election workers amid rampant and largely unsubstantiated claims of voter fraud as the state continues a third count of the presidential vote.

Sterling called on Trump to "step up" and say, "Stop inspiring people to commit potential acts of violence," adding, "Someone's gonna get hurt. Someone's gonna get shot. Someone's gonna get killed."

“All of you who’ve not said a damn word are complicit in this," he said, detailing death threats one Georgia election worker has faced.

A more mild-mannered Raffenspeger also chastised Trump Wednesday for how he responded on Twitter to Sterling's pleas for him to condemn violence.

"Even after this office request that President Trump trying to quell the violent rhetoric, being born out of his continuing claims of winning the states where he obviously lost, he tweeted out, 'Expose the massive voter fraud in Georgia.' This is exactly the kind of language that is at the base of the growing threat environment for election workers who are simply doing their jobs," Raffensperger said.

-ABC News' Quinn Scanlan

After debuting his nominees to lead economic policy posts in the incoming administration Tuesday, Biden is slated to participate in a virtual roundtable with workers and small business owners affected by the coronavirus pandemic and economic crisis in Wilmington, Delaware, Wednesday afternoon.

For the third day he and Vice President-elect Kamala Harris will also receive the President’s Daily Brief, following a 16-day standoff with the Trump administration holding up federally-allocated resources to aid in the transition.

Although Trump still publicly refuses to concede the loss -- vowing to press forward with legal battles despite a string of losses -- at a White House holiday party Tuesday night, he acknowledged his potential departure from the White House by teasing running again in 2024.

"It's been an amazing four years. We are trying to do another four years. Otherwise, I’ll see you in four years," the president can be heard saying on video of the event reviewed by ABC News. Multiple sources also confirmed to ABC News that the president made the remarks.

In advance of Trump leaving office, sources tell ABC News the president is considering doling out preemptive pardons to members of his inner circle. Names for consideration include the president’s three oldest children, his personal attorney Rudy Giuliani -- who has denied asking for one -- and son-in-law Jared Kushner.

It all comes as Attorney General William Barr told the Associated Press Tuesday that the Justice Department has uncovered no evidence of widespread voter fraud that would tip the results of the presidential election -- directly undercutting allegations being made by Trump and his legal team.

At a Christmas party at the White House Tuesday night, President Donald Trump teased running for president again in 2024 while noting that he's still "trying to do another four years."

"It's been an amazing four years. We are trying to do another four years. Otherwise, I’ll see you in four years," the president can be heard saying on video of the event reviewed by ABC News.

Multiple sources also confirmed to ABC News that the president made the remarks at the White House party.

The president also falsely told the group of mostly Republican National Committee members gathered for the party that he won the election, calling it rigged and notably saying he will "always" call it rigged.

"It's certainly an unusual year. We won an election. But they don’t like that ... I call it a rigged election, and I always will," Trump said.

Since losing reelection, Trump has privately been telling advisers that he’s considering a 2024 campaign, as ABC News has previously reported.

The indoor party notably takes place as COVID-19 cases surge around the country and, according to the video, many people inside were not wearing masks despite the White House saying they would be mandatory.

Stephanie Grisham, the chief of staff and spokeswoman for the first lady, told ABC News in a statement on Nov. 22 that "masks will be required."

"The People’s House will celebrate Christmas and Hanukkah while providing the safest environment possible. This includes smaller guest lists, masks will be required and available, social distancing encouraged while on the White House grounds, and hand sanitizer stations throughout the State Floor," Grisham said. "Guests will enjoy food individually plated by chefs at plexiglass-protected food stations. All passed beverages will be covered. All service staff will wear masks and gloves to comply with food safety guidelines. Attending the parties will be a very personal choice. It is a longstanding tradition for people to visit and enjoy the cheer and iconic decor of the annual White House Christmas celebrations."

The Centers for Disease Control and Prevention have advised indoor holiday gatherings should be small and only include close family and friends who are part of your household.

Both the White House and the first lady's office declined to comment on the White House event.

--ABC News' Will Steakin, Katherine Faulders and Ben Gittleson