Trump-Biden transition updates: Trump continues to tout he won election at Ga. rally

Georgia Secretary of State Brad Raffensperger spoke before reporters Monday morning at the state capitol building in Atlanta and announced that his office has opened investigations into four third-party groups that he claimed are "working to register people in other states to vote here in Georgia." 

However, Raffensperger also maintained the 2020 presidential election was the most secure election in the state's history and slammed against those peddling misinformation surrounding it. 

"Once this recount is complete, everyone in Georgia will be able to have even more confidence in the results of our elections, despite the massive amounts of misinformation that is being spread by dishonest actors," Raffensperger said, adding the state's machine recount is on schedule to finish by the midnight Wednesday deadline. 

"There are those who are exploiting the emotions of many Trump supporters with fantastic claims, half-truths, misinformation, and frankly, they're misleading the president, as well, apparently," he added. 

Ahead of Senate runoffs Jan. 5, Raffensperger also warned, "Anyone telling you to boycott an election is not on your side."

Gabriel Sterling, the statewide voting system implementation manager, blasted lawsuits questioning the credibility of the state's electoral process as "fever dreams"and shot down the conspiracies about the election including that Dominion's voting machines flipped votes. 

"The ridiculous things claimed in these lawsuits are just that, they're insanities, fever dream, made up, internet cabal," he said. "Nothing was shipped from overseas. No votes were switched. We did a hand audit that proved no votes were switched."

Sterling said he feels like he's "playing a game of Whac-A-Mole"-- that every time they shoot down one unfounded claim, another "new crazier one" pops up. 

-ABC News' Quinn Scanlan

Trump continues to discredit the voting system in Georgia, slamming GOP Gov. Brian Kemp and Secretary of State Brad Raffensperger -- and in doing so, risks undercutting GOP efforts there by discouraging Republican voters ahead of two runoffs on Jan. 5 that will determine the balance of power in the United States Senate. 

Referring to Kemp as "hapless," Trump called on him via Twitter Monday morning to use his "emergency powers... to overrule his obstinate Secretary of State" and do signature matching for the absentee ballots again.

It’s unclear what emergency powers the president is referring to that the governor could execute, but signature matching for absentee ballots has already been conducted twice. 

Signatures are matched first when a voter applied for an absentee ballot and then again when the voter returned their absentee ballot. Once the signature accompanying the returned ballot is verified, the ballots are separated from the envelopes and there is no way to re-match them because, under the Georgia state Constitution, a voter is entitled to a secret ballot. However, the envelopes are kept on file for two years.

It comes ahead of Trump traveling to Georgia on Saturday to campaign for the Republican candidates in the Senate runoffs. 

-ABC News’ Quinn Scanlan

Biden is slated to receive his first President's Daily Brief Monday marking a milestone for the president-elect following a nearly three-week delay in the Trump administration recognizing him as the winner of the 2020 presidential election.

It comes after Biden, who has pressed forward with his transition despite Trump’s roadblocks, announced he’ll enter the White House with an all-female communications team and unveiled his economic team Monday morning, naming former Federal Reserve Chair Janet Yellen as his nominee for Treasury Secretary, the first woman to hold the top job if confirmed.

In another challenge to his transition, the president-elect fractured his right foot while playing with his dog, Major, over the weekend, and is expected to wear a walking boot for several weeks. 

Trump, meanwhile, isn’t acknowledging the loss even after appearing to come to terms with it on Thanksgiving and saying he would leave the White House if the Electoral College affirms Biden’s win. 

In a defiant interview with Fox Business Sunday, Trump fired off false claims to sow doubt in the electoral process and vowed to continue legal battles with his team on Monday targeting Arizona’s certification deadline. Trump’s personal attorney Rudy Giuliani and campaign adviser Jenna Ellis are expected to appear from D.C. at another non-official "hearing" of state GOP lawmakers at a Phoenix hotel Monday. 

The day also brings a certification deadline in Wisconsin, where a recount paid for by the Trump campaign wrapped over the weekend brought Biden 87 additional votes.

Biden has formally announced his economic team, including nominee Janet Yellen, who would be the first woman to lead the Treasury Department, and the first person to have served as Treasury Secretary, Chair of the Council of Economic Advisers and Chair of the Federal Reserve if confirmed.

Neera Tanden, nominated to to lead the Office of Management and Budget, would be the first woman of color in the role, if confirmed.

Here's a breakdown of the economic positions announced Monday: 

• Janet Yellen, Secretary of the Treasury
• Neera Tanden, Director of the Office of Management and Budget
• Wally Adeyemo, Deputy Secretary of the Treasury
• Cecilia Rouse, Chair of the Council of Economic Advisers
• Jared Bernstein, member of the Council of Economic Advisers
• Heather Boushey, member of the Council of Economic Advisers

-ABC News' Molly Nagle