The Senate voted on Friday to override President Donald Trump's veto on the defense spending bill in a rare New Year's Day session.

The stinging rebuke by members of Trump's own party represents the first time in his term that a veto has been overturned.

The vote was 81-13. A supermajority is needed to override a presidential veto.

Sen. Mitt Romney, R-Utah, confirmed today that Mitch McConnell, the Senate majority leader, called the upcoming joint session of Congress on Jan. 6, which will affirm the results of the presidential election, "the most consequential vote" of his lengthy tenure.

"I see that as a statement that he believes it's a -- it's a referendum on our democracy," Romney told reporters.

Sources said that McConnell asked Sen. Josh Hawley, R-Mo., on a New Year's Eve call with Republicans to explain to his colleagues why he is planning to object to the certification of Biden’s electoral win during the joint session. McConnell had privately warned his colleagues weeks ago against doing this as it would put his conference in the position of having to oppose Trump (and thereby his base) publicly.

Hawley, in joining the last-ditch bid by Trump's House allies to overturn the election results, said he objected to states not following their election laws.

"At the very least, Congress should investigate allegations of voter fraud and adopt measures to secure the integrity of our elections," Hawley said in a statement. There has been no evidence of widespread election fraud.

-ABC News' Trish Turner

In a very rare New Year’s Day session, Senate GOP leadership rejected two attempts to debate and vote on the House-passed CASH Act, which would give most Americans $2,000 in direct COVID relief payments. It was an effort by both Sens. Chuck Schumer and Bernie Sanders.

Republicans are continuing to argue that the House bill —- which would allow those making up to $350,000 to receive some cash under the act, albeit a smaller amount than those making less -- amounts to "socialism for the rich."

The chamber’s socialist, Sen. Sanders -- continued to argue that Republicans were “hypocrites” —- blocking this effort but approving big tax breaks for the rich.

He was joined by conservative Sen. Josh Hawley, who slammed the fight by his own leadership.

“With all due respect, this doesn’t seem to be Republicans against Democrats. This seems to be the Senate against United States of America,” said Hawley.

-ABC News' Trish Turner

The Senate is set to cast a preliminary vote this afternoon on overriding President Trump's veto of the National Defense Authorization Act -- which would be the first of his term.

The House voted overwhelmingly earlier this week to override Trump's veto of the $740 billion legislation, which funds the military and that members from both parties have said is vital to both the troops, who get a raise under the measure, and national security.

Trump has called the bill a "gift" to China and Russia.

In vetoing the measure (which has passed every year for 59 years), Trump demanded that Congress include a repeal of Section 230 of the Communications Decency Act, which gives broad legal immunity to tech companies over contents posted by users. He also wanted lawmakers to nix a provision authored by Sen. Elizabeth Warren that requires DOD to rename military bases and installations that honor Confederate generals.

Congress originally passed the measure with veto-proof majorities, and the House recently voted to override the veto. If the Senate votes to override - as it is expected to -- the bill would become law.

Today's test vote (which should be similar - if not identical - to the final vote) is expected to show more than the two-thirds majority required to override Trump's veto.

-ABC News' Trish Turner

In a previously recorded campaign-style video posted to Twitter Thursday, President Donald Trump touted what he views as his many presidential accomplishments: producing COVID-19 vaccines, repairing the economy and stopping "endless foreign wars" in the Middle East.

When it comes to vaccines, Trump said, "Our most vulnerable citizens are already receiving the vaccine and millions of doses are quickly being shipped all across our country."
The president promised that "by early next year the vaccine will be available to every American."

The Trump administration had promised that 20 million people would be vaccinated by the end of the year. As of Wednesday morning, 2,794,588 Americans had received vaccine doses and 12.4 million doses had been distributed, according to the Centers for Disease Control and Prevention.

Trump also boasted about the economy, saying, "Through the Paycheck Protection Program, we saved or supported more than 51 million American jobs, and we're doing numbers now like nobody's ever seen before, including having the highest stock market in the history of the world."

"We have slashed the unemployment rate from 14.7%, all the way down to 6.7%," Trump said. "Our economy is growing at the most rapid rate ever recorded. ... Nobody can compete with us in terms of going down less, and going up by far the fastest and the best. Whenever America's challenged, we always rise to the occasion."

Many economists, however, have argued that the economy is rebounding in a K-shape, as opposed to a V-shape, with the rich getting richer and the working class still struggling.

The president also touched on foreign affairs.

"We have secured our borders and paused immigration to protect American workers," Trump said. "And after years of endless foreign wars we are signing historic peace deals in the Middle East. It's all ending in the Middle East. We have to hope it keeps going. It's so easy if you know what you're doing."

While Trump has successfully pushed to normalize relations between Israel and many Middle Eastern countries, it's not accurate to say they are "peace deals" and they have come at the expense of Palestinians and aligned the countries against Iran. Iran, and its nuclear ambitions, continues to be a thorn in America's side. Trump has drawn down forces from Afghanistan and Iraq, but promised negotiations between the Afghan government and the Taliban fell apart and ISIS and al-Qaida affiliates are taking advantage of the insecurity in Syria, Northern Africa and elsewhere.

ABC News' Elizabeth Thomas contributed to this report.