Gabriel Sterling, the statewide voting system implementation manager in Secretary of State Brad Raffensperger's office, unleashed on the president from Atlanta Tuesday afternoon, as well as GOP Sens. David Perdue and Kelly Loeffler, chastising them for not forcefully condemning threats of violence against election officials, making several direct pleas to Trump in his remarks.

"Mr. President, it looks like you likely lost the state of Georgia. We're investigating, there's always a possibility, I get it, and you have the rights to go through the course. What you don't have the ability to do -- and need to step up and say this -- is stop inspiring people to commit potential acts of violence. Someone's gonna get hurt. Someone's gonna get shot. Someone's gonna get killed," Sterling said.

"Everything we're seeing right now, there's not a path. Be the bigger man here, and stop -- step in, tell your supporters, don't be violent, don't intimidate. All that's wrong. It's un-American," he continued.

Sterling said that Trump calling Georgia Secretary of State Brad Raffensperger "an enemy of the people" on Thanksgiving "helped opened the floodgates to this kind of crap."

"You have to be responsible in your rhetoric," he said. "That shouldn't be too much to ask for people who asked for us to give them responsibility."

Explaining his anger, Sterling said that the "straw that broke the camel's back" was when someone took a video of a 20-year-old contractor working for Dominion in Gwinnett County claiming it showed him manipulating election data, but that was not was he was doing. He said the man is getting death threats -- that there's been "a noose put out saying he should be hung for treason" -- and since he has a unique name, people have tracked down his family, too and they're also being harassed.

"Mr. President, you have not condemned these actions or this language. Senators, you have not condemned this language or these actions. This has to stop. We need you to step up, and if you're gonna take a position of leadership, show some," Sterling said. "All of you who’ve not said a damn word are complicit in this." br/>
-ABC News' Quinn Scanlan

Biden's team has made contact with two of most prominent leaders on the White House coronavirus task force -- Dr. Anthony Fauci, the nation’s top expert on infectious disease, and Dr. Deborah Birx, coronavirus response coordinator, as his transition team maintains its focus on the ongoing pandemic and the federal response they will inherit in 50 days.

Biden has held separate conversations with the two White House coronavirus task force officials, according to a transition official. Birx, whose colleagues told ABC News she would like to continue serving in a Biden administration, met with members of Biden's team on Monday.

A global health expert who was tapped from running the federal government’s program combating HIV/AIDS to serve on the task force in the February, Birx told CBS on Sunday that she was preparing to brief Biden's team on the nation's coronavirus response.

In an interview with McClatchy last week, Fauci said he assumes he will stay in his position as director of the National Institute of Allergy and Infectious Diseases, a post he has held for 36 years, but that he would also "seriously consider" serving in another capacity if Biden asked.

"I’m perfectly comfortable with the role that I’m in, but certainly if the president of the United States wants me to do something else, I’d seriously consider it," Fauci said. "Quite frankly, I don’t anticipate that I’m going to be doing anything other than what I’m doing now. But then again, we have a president-elect who may have other plans. I don’t know."

Ahead of Election Day, Biden promised he would "hire Fauci" and "fire Trump" if elected, amid Trump knocking Fauci's credibility and public health guidance.

-ABC News’ Benjamin Siegel and Ben Gittleson

Trump’s reelection campaign filed a petition to the Wisconsin Supreme Court on Tuesday, challenging the outcome of the presidential election that was certified on Monday with the president’s personal attorney, Rudy Giuliani, among those filing.

The legal action comes after the Trump campaign demanded recounts in Milwaukee and Dane counties, only to see that effort turn up 87 additional votes for his opponent, Biden. It also comes as Attorney General William Barr said in an [interview] () Tuesday that the Justice Department has uncovered no evidence of widespread voter fraud that would tip election results.

This latest petition alleges that poll workers illegally altered ballot envelopes, added missing information on voters’ behalf, counted ballots submitted early without sufficient voter identification, or collected ballots at unauthorized locations. In all, the Trump campaign claims that more than 211,000 votes were improperly counted. Trump lost the state to Biden by more than 20,600 votes.

Normally, this lawsuit would be filed with a circuit court but given the urgency the Trump campaign directly petitioned the state’s conservative-leaning high court. The court has not indicated if it will hear the case, or respond before the Dec. 8 “safe harbor” deadline, after which the election results are considered conclusive.

Democrats have not responded to the petition, but broadly have characterized the Trump campaign’s legal efforts as a “sideshow” that show no prospect of changing the outcome of the 2020 election. A series of court rulings to date have found no evidence of fraud or improper actions by elections officials in the states where the campaign has brought legal action.

-ABC News' Soo Rin Kim and Cheyenne Haslett

Attorney General William Barr told the Associated Press in an interview Tuesday that the Justice Department has not uncovered widespread fraud in the 2020 presidential election.

"To date, we have not seen fraud on a scale that could have affected a different outcome in the election," Barr told the AP.

The attorney general’s comments come into contrast with claims from the president and his lawyers that the election was stolen. Trump has still refused to concede to Biden.

"Most claims of fraud are very particularized to a particular set of circumstances or actors or conduct. They are not systemic allegations and. And those have been run down; they are being run down," Barr said.

"Some have been broad and potentially cover a few thousand votes. They have been followed up on."