Following Trump's threat to veto the $900 billion COVID-19 relief bill, Sen. Bernie Sanders, I-Vt., will speak with ABC News Chief White House correspondent Jonathan Karl about the latest efforts to get relief benefits to millions of Americans on "This Week" Sunday.

Karl will also speak with Maryland Gov. Larry Hogan on the state of the Republican Party and U.S. Surgeon General Jerome Adams about the latest on the COVID-19 pandemic after heavy air travel this holiday season.

The Powerhouse Roundtable will also take on Trump's recent flurry of pardons for his political allies.

Check local listings for air time.

Biden released a statement on Saturday afternoon amping up the pressure on Trump to sign the COVID-19 relief bill passed by Congress.

Biden said the “abdication of responsibility” by Trump has “devastating consequences” for Americans while reiterating that while the bill is "critical," it is also just a first step toward getting struggling families and businesses the help they need.

"It is the day after Christmas, and millions of families don’t know if they’ll be able to make ends meet because of President Donald Trump’s refusal to sign an economic relief bill approved by Congress with an overwhelming and bipartisan majority," the statement reads.

"This abdication of responsibility has devastating consequences. Today, about 10 million Americans will lose unemployment insurance benefits. In just a few days, government funding will expire, putting vital services and paychecks for military personnel at risk. In less than a week, a moratorium on evictions expires, putting millions at risk of being forced from their homes over the holidays," it continues. "Delay means more small businesses won’t survive this dark winter because they lack access to the lifeline they need, and Americans face further delays in getting the direct payments they deserve as quickly as possible to help deal with the economic devastation caused by COVID-19. And while there is hope with the vaccines, we need funding to be able to distribute and administer them to millions of Americans, including frontline health care workers."

The bill "needs to be signed into law now," the statement says. "But it is also a first step and down payment on more action that we’ll need to take early in the new year to revive the economy and contain the pandemic."

-ABC News' John Verhovek

On Saturday, the day expanded unemployment benefits are set to lapse after Trump refused to sign the bipartisan COVID-19 relief and spending bill overwhelmingly approved by Congress this week, the president tweeted again about one of his main sticking points -- the amount of money the bill allocates to send directly to Americans.

"I simply want to get our great people $2000, rather than the measly $600 that is now in the bill. Also, stop the billions of dollars in 'pork,'" he tweeted.

It is unclear if the president, who received the bill at Mar-a-Lago Christmas eve, has any intention of signing the bill or vetoing it. If he vetoes it, Congress could override his veto. But he could also do nothing and wait for the current Congress to end, forcing the new Congress to start from scratch on another bill.

If Trump doesn't sign the bill, it could also lead to a government shutdown.

Trump also tweeted Saturday morning his grievances about the results of the presidential election and what he views as a lack of support in overturning the results.

"Mitch & the Republicans do NOTHING, just want to let it pass. NO FIGHT!" he wrote in one tweet.

In another, he dug into the DOJ and the FBI, tweeting: "The 'Justice' Department and the FBI have done nothing about the 2020 Presidential Election Voter Fraud," again citing baseless claims about the presidential election.

He repeated those baseless claims in yet another tweet directed at the Supreme Court.

"The U.S. Supreme Court has been totally incompetent and weak on the massive Election Fraud that took place in the 2020 Presidential Election," he wrote, continuing to make debunked claims.

-ABC News' Mariam Khan, Allison Pecorin and Ben Gittleson

As Americans wait to learn whether Trump will sign a must-pass spending bill and COVID-19 relief package, Trump tweeted on Friday afternoon a reiteration of his demand that Americans receive $2,000 payments as opposed to the $600 in the current legislation.

"Why would politicians not want to give people $2000, rather than only $600?" he wrote.

The current bill took months to negotiate and was finalized just days before millions lose benefits if pandemic-era provisions expire. Then Trump demanded more money be sent directly to Americans.

House Democrats seized on Trump's demand on Thursday, proposing $2,000 payments in a measure that was blocked by members of Trump’s own party.

Trump has spent the past two days at his golf club, while Vice President Mike Pence is reportedly spending the holidays at Vail.

Shortly after his tweet on the bill, the president tweeted that he’s going to do a video call with troops around the world, but that the “Fake News” is “not invited!”

-ABC News' Ben Gittleson, Mariam Khan and Allison Pecorin

A Dominion Voting Systems employee has filed a defamation lawsuit against President Donald Trump, attorneys Sidney Powell and Rudy Giuliani, among others, alleging they helped elevate a "false and baseless" conspiracy theory about him as part of their election rigging [claims[() against the voting machine company.

The suit marks the start of what could be an onslaught of litigation against the president and his allies, who mounted challenges to the election based on false allegations of fraud and fierce conspiracy theories. Some conservative outlets in recent days have begun airing retractions as the threat of litigation looms.

Eric Coomer, the Director of Product Strategy and Security for Dominion, says he has faced death threats and harassment as a result of the "baseless and unequivocally false" conspiracy theory about him, which claimed he had admitted to rigging Dominion machines against Trump on an "Antifa conference call."

"Without concern for the truth or the consequences of their reckless conduct, Defendants branded Dr. Coomer a traitor to the United States, a terrorist, and a criminal of the highest order," Coomer wrote in his complaint. "While this theory has been thoroughly rejected, its immediate and life-threatening effects remain very real."

The suit, filed in state court in Colorado, is separate from the heavy legal challenge Dominion as a company is expected to mount on its own against Sidney Powell.

In his complaint, Coomer says the threats have escalated to the point where he had to leave his home and "sever ties" with friends and family to stay in seclusion after the theory-- part of a broader conspiracy theory that the Dominion voting machine company rigged the election for Biden-- went viral on social media.

-ABC News' Olivia Rubin