More than 42 million Americans have cast early ballots ahead of tomorrow's midterm elections, surpassing the numbers from 2018, the US Elections Project has said.
Americans will go to the polls tomorrow to elect 435 members of the House of Representatives, one-third of the Senate and a host of state and local posts.
Most of the 50 US states allow voters to cast ballots early, either in-person or by mail, a practice which became widespread during the 2020 presidential election, which was held at the height of the Covid-19 pandemic.
According to the US Elections Project, as of this evening, there have been more than 19.3 early votes cast in-person and 22.7 million by mail for a total of 42.03 million.
It said 39.1 million people had voted by the same point in the 2018 midterms.
Republican politicians have lodged technical objections to early voting in several states where elections could be close.
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In Pennsylvania, for example, the state supreme court has ruled that mail-in votes cannot be counted if they do not bear a written date on the envelope - a decision that could potentially affect thousands of ballots.
In Wisconsin, absentee votes can be thrown out if the address of the witness - whom the state requires watch a ballot envelope being sealed - is incomplete.
Former Republican president Donald Trump alleged last week that "unverified" ballots had been mailed to voters in the key state of Pennsylvania, a claim which was debunked by state elections officials.
After losing the 2020 presidential election to Democrat Joe Biden, Mr Trump also made false claims of election fraud, which have been echoed by many members of his Republican Party.
Mr Biden and Mr Trump have been headlining a frantic last day of campaigning on the eve of the election that will shape the rest of the US president's term, and could pave the way for a White House comeback by his predecessor.
After months of divisive campaigning, Mr Biden and the Democrats face a gargantuan struggle to hang on to Congress, in a race that he has cast as a "defining" moment for American democracy - though kitchen-table issues like inflation have largely dominated voters' minds.
Republicans appear set to snatch a majority tomorrow in the lower House of Representatives, and many Democrats fear the Senate also slipping away in a defeat that would see Mr Biden's foes in near total charge of legislation during his next two years as president.
Polls show most Americans are anxious about the economy and feel the country is on the wrong track, emboldening Republican candidates in districts that once looked out of reach.
With all 435 seats in the House of Representatives up for grabs alongside a third of the 100-member Senate and a slew of state posts, Democrats were putting a brave face on their prospects.
"The party in the White House usually loses during midterms but the reality is we still have a very strong pathway, not just to keeping the Senate but really picking up seats," Senator Cory Booker told ABC.
Democratic candidates have been lent star power on the campaign trail by the party's most popular elder statesmen, including presidents Barack Obama and Bill Clinton.
Republicans have tapped a narrower roster of their own big hitters, with the spotlight turning in recent weeks to Mr Trump - who has been teasing a probable new presidential run in 2024.
The president holds a rally in Maryland while Mr Trump will campaign in a turbulent US Senate race in Ohio.
The political landscape has been tilting away from Democrats since the summer, with polls showing Republicans odds-on for a firm House majority.
"This is going to be a wake-up call to President Biden," was the bullish weekend prediction of Glenn Youngkin, Virginia's Republican governor.
The Senate is more of a toss-up but Democratic hopes of keeping the upper chamber, which they control thanks to tiebreaking votes from Vice President Kamala Harris, hang in the balance.
Dave Wasserman of nonpartisan Cook Political Report said Republican candidates have "a little more upside" with late-deciders.
But "I don't think the bottom has completely dropped out for House Democrats," Wasserman told MSNBC.
He estimated a potential Republican gain of 15-25 House seats, however, while "Republicans might gain the one seat they need to win control of the Senate."
Races in Pennsylvania, Nevada, Arizona, Georgia, Wisconsin, New Hampshire and Ohio have narrowed to projected photo finishes, and any one of them could swing the balance of power.
Democrats have focused their closing arguments on voting rights, protecting abortion access and welfare -- and on the threat posed by growing support among Trump Republicans for political conspiracy theories.
The Republicans counter that a vote for Democrats means more soaring inflation and rising violent crime, seeking to make the midterms a referendum on the president.
With his approval rating marooned around 42%, Mr Biden has largely avoided the most contentious states.
But he rallied alongside Mr Obama in Pennsylvania on Saturday, as part of a hectic late campaign agenda that has also taken him to Illinois, Florida and even New York.
The president rebuked extremist supporters of "defeated president" Trump, telling the crowd: "Your right to choose is on the ballot. Your right to vote is on the ballot."
'Decline and fall'
Staging a rival weekend rally in swing state Pennsylvania, Mr Trump - who continues to push false claims the 2020 election was stolen - accused the "radical, crazy" Democrats of bringing about "the decline and fall of America."
Mr Biden has major achievements to tout, including curbs on prescription drug pricing, ramped-up microchip manufacturing and record investments in infrastructure.
But Democrats have struggled to turn these legislative victories, along with strong job growth, into enthusiasm in the heartland.
Still, 48% of likely voters said they prefer a Democratic-controlled Congress in a final national NBC News poll, while 47% want Republicans in charge.
But 80% of Republican-leaning voters say they are certain to turn out or have already done so, according to a Washington Post-ABC poll, six points above the Democratic figure.
House Minority Leader Kevin McCarthy, who would likely replace Nancy Pelosi as speaker if Republicans take over, said he would prioritize investigations into the chaotic Afghanistan pullout and coronavirus origins - and left open the possibility of launching impeachment proceedings.
"We will never use impeachment for political purposes," Mr McCarthy told CNN.
"That doesn't mean if something rises to the occasion, it would not be used at any other time."