Harris, Trump conclude campaigning - now it's up to the voters as Election Day 2024 gets underway

Nearly two years after launching his campaign to return to the White House, former President Trump's bid to win back his old job is now in the hands of America's voters, as Election Day 2024 has arrived. 

Facing off against the Republican presidential nominee is Vice President Kamala Harris, who just three and a half months ago replaced her boss - President Biden - atop the Democrats' national ticket.

With roughly 81 million ballots already cast across the country in early voting, and in-person day-of voting now getting underway, both major party nominees are optimistic about their chances in this historic showdown.

"Momentum is on our side," Harris told supporters at a rally in Allentown, Pennsylvania on Monday. "Can you feel it."

HEAD HERE FOR FOX NEWS UPDATES ON THE 2024 ELECTION 

And hours later, at a rally in Pittsburgh, the vice president reiterated, "make no mistake, we will win.

Trump, also campaigning in battleground Pennsylvania, told supporters "we've been waiting for this. I've been waiting four years for this."

HARRIS, TRUMP, HOLD ELECTION EVE DUELING RALLIES IN THE BIGGEST OF THE BATTLEGROUNDS

And even though the final national polls and key swing state surveys pointed to a margin-of-error race, the former president has touted that "we have a big lead. We have a big lead."

It was a 3-to-3 split decision in Dixville Notch, the tiny town in New Hampshire's North Country that for six decades has been grabbing plenty of attention by holding its vote at midnight on Election Day.

Trump and Harris held dueling rallies on Election Eve in Pennsylvania, which, with 19 electoral votes at stake, is the biggest prize among the seven key battleground states.

Harris closed out her campaign schedule with a large late night rally in Philadelphia, by the famed "Rocky Steps" outside the city's Art Museum.

Around the same time Harris was in Philadelphia, Trump held his final rally in Grand Rapids, Michigan, the same spot where he closed out his 2016 and 2020 campaigns.

Pennsylvania and Michigan, along with Wisconsin, North Carolina, Georgia, Arizona and Nevada, are the seven swing states whose razor-thin margins decided President Biden's 2020 victory over Trump and will likely determine whether Trump or Harris wins the 2024 election.

CHECK OUT THE FOX NEWS ELECTION HUB

Harris, Trump, their running mates and top surrogates, have fanned out across the seven battlegrounds the past couple of months. And the two presidential campaigns and allied super PACs have spent nearly all the $2.3 billion they've shelled out to run ads in the White House race in the battleground states.

The vice president and the former president closed out their campaigns with very divergent messages.

Harris, who for a second straight day avoided mentioning Trump by name, closed with a positive and upbeat message as she painted a unified future for the nation.

Trump painted a negative picture of the country the past four years under the Biden administration, as he railed against Democratic policies and spotlighted the dangers of unchecked immigration.

For Trump, the 2024 campaign has been a grueling two-year marathon. He announced his candidacy at his south Florida Mar-a-Lago club days after the 2022 midterm elections. After a slow start, the former president easily dispatched a field of GOP primary opponents - which last year briefly expanded to over a dozen contenders - and ran the table earlier this year in the Republican presidential primaries.

NOVEMBER SURPRISE: DISMAL JOBS REPORT HANDS TRUMP INSTANT AMMUNITION TO FIRE AT HARRIS

Trump, who was indicted in four different criminal cases, saw his support surge and his fundraising soar in the late spring, after he made history as the first former or current president convicted of felonies.

A month later, Biden suffered a major setback after a disastrous late June debate performance against Trump reignited longstanding questions over whether the 81-year-old president was physically and mentally up for another four grueling years in the White House - and sparked calls from within his own party for him to step down.

Trump's polling advantage over Biden widened, and the former president was further politically boosted after surviving an assassination attempt on his life at a rally in Butler, Pennsylvania, two days before the start of the Republican National Convention in July.

But the race was instantly turned upside down days later, as Biden ended his re-election bid and endorsed his vice president. Democrats quickly coalesced around Harris, and her fundraising surged as her poll numbers soared.

The Harris honeymoon continued through the late August Democratic National Convention, and into September, when most pundits declared her the winner of the one and only presidential debate between her and Trump. 

But as the calendar moved from September into October, Trump appeared to regain his footing, and public opinion surveys indicated the former president gaining momentum.

Veteran Republican strategist and Fox News contributor Karl Rove called the Harris-Trump showdown a "coin toss."

But longtime Republican consultant Alex Castellanos, taking issue with the polls, pointed to voter registration gains by Republicans.

"I think the pollsters are getting this wrong. We're all missing something because they're giving us the same poll over and over again. .. Somebody's missing something."

And Castellanos, a veteran of numerous presidential campaigns, argued "what I think they're missing a massive shift in voting registration underneath all of this. Thirty-one states have voter registration by party. Thirty of them in the past four years have seen movement by Republicans."

Longtime Democratic pollster Mark Penn, on Fox News' "Special Report," pointed to an apparent surge in early voting by Republicans - after Trump, long a vocal critic of early voting - in recent days embraced the GOP's longstanding effort to make Republicans more accepting of early voting, and said "the only fact we know is that Republicans have done a lot better in the mail in and early voting that they ever have."

Harris, a California resident, cast her vote by mail ahead of Election Day. 

The Trump campaign said that the former president would cast his ballot in-person on Election Day in Palm Beach, Florida, where he resides.

Trump, according to his campaign, also planned to spend Election Day with family, friends, and staff, and also do some phone-based tele rallies to targeted spots. 

The former president was set to hold his Election Night headquarters at a convention center in West Palm Beach, Florida.

Harris was expected to spend part of Election Day making her case in radio interviews. And the vice president was scheduled to hold her Election Night headquarters at her alma mater, the historically Black Howard University in Washington, D.C.

During the closing final week of the campaign, Trump - who for four years has made false claims that his 2020 loss was due to a rigged election - appeared to be trying to discredit the 2024 election.

Trump, on Sunday, once again argued without providing proof that the Democrats were trying to cheat.

"They are fighting so hard to steal this damn thing," the former president charged on Sunday.

Get the latest updates from the 2024 campaign trail, exclusive interviews and more at our Fox News Digital election hub.