WEST PALM BEACH, Fla. — It has been nearly nine years since Donald Trump descended a golden escalator and entered the hearts and minds of what was to become the massive MAGA movement.

The packed rallies, which number in the hundreds, and his relentless overtures seeking support for another White House term end Tuesday near his Mar-a-Lago home.

“Think of this,” a wistful Mr. Trump told a crowd Monday in Raleigh, North Carolina, where he has held at least 50 political rallies. “I won’t be doing this anymore with North Carolina, and I won’t be doing this anymore after today. I’m just thinking, as I’m going through this, that this will be our final moment.”

Election Day could be the dawn of a new phase of Mr. Trump’s dominance over the Republican Party as he looks to restore security at the southern border, cut inflation and reduce taxes — all top voter concerns.

It also could signal the end of his political reign, one of the longest of any party in modern history, if Vice President Kamala Harris beats him to the 270 electoral votes needed to capture the White House.

Ms. Harris sought to extinguish the Trump era and install an agenda to increase abortion access, provide tax incentives for first-time homebuyers and small business startups, and raise taxes on millionaires and billionaires.

Mr. Trump’s enduring hold over the Republican Party was just one element of a campaign season marked by unprecedented twists and turns.

His political future now rests on seven battleground states where he is essentially tied with his Democratic opponent. Ms. Harris’ ascendancy to the top of her party’s ticket was equally improbable.

The two candidates embarked on final, frantic campaign blitzes Monday after barnstorming battleground states throughout the weekend.

Ms. Harris spent Monday in Pennsylvania. Her campaign sees the state as the most important, along with Wisconsin and Michigan, in her “blue wall” strategy to win the election.

In Allentown, she told supporters she believed the momentum was on her side.

“We have the opportunity in this election to turn the page on a decade of politics that has been driven by fear and division,” Ms. Harris said. “America is ready for a fresh start.”

Mr. Trump appealed to voters in four swing states. He started the day in North Carolina before making two stops in Pennsylvania and marking his grand finale campaign appearance in Michigan, a state he won in 2016 but lost in 2020.

He told supporters that if he wins, he will restore the successes he achieved in his first term. As he has done in nearly every other public appearance, the former president, who lost narrowly to President Biden in 2020, raised concerns about election irregularities that he warned could swing the results unfairly to his opponent.

“Once again, everyone will prosper, every family will thrive, and every day will be filled with opportunity and hope and the American dream itself. But for that to happen, we must defeat Kamala and stop her radical left agenda with a landslide that is too big to rig,” Mr. Trump told supporters in Raleigh, North Carolina.

Monday’s polls based on averages calculated by nonpartisan analyst Ron Faucheux showed the race deadlocked.

Ms. Harris was ahead in the blue wall states by less than half a percentage point. Mr. Trump was ahead in the remaining four swing states of Nevada, North Carolina, Arizona and Georgia, by two-tenths of a point to 2.4 points. All the results are within the margin of error, meaning either candidate could win any battleground state.

The former president faces voters as a convicted felon and with three additional looming criminal cases that his supporters say are politically motivated attempts to kneecap his campaign. His opponents say it makes him unfit for office.

He arrived at Election Day after surviving two assassination attempts and defeating more than a dozen opponents in the Republican primary race, becoming the first in his party since Richard Nixon to be nominated three times to the top of the ticket.

Ms. Harris’ campaign is also in uncharted territory. Democratic Party officials hastily ushered her to the top of the ticket in July after Mr. Biden, 81, collapsed in the polls. He had a disastrous debate performance that appeared to show age-related cognitive decline.

Ms. Harris never stood before voters in a presidential primary.

She quit the 2020 presidential race before the Iowa caucuses and became Mr. Biden’s running mate after he vowed to select a woman for the job.

After replacing Mr. Biden, Ms. Harris quickly closed a gap with Mr. Trump in the polls and raised $1 billion. Her momentum stalled in September despite start-studded rallies and endorsements, leaving the race gridlocked.

Ms. Harris’ dedication to Pennsylvania on the last day of the campaign had some analysts second-guessing her decision to bypass Gov. Josh Shapiro as her running mate in favor of Minnesota Gov. Tim Walz. The far more liberal Mr. Walz has not helped Ms. Harris win over the rural and blue-collar voters like the campaign had envisioned.

Ms. Harris detoured her campaign plane to New York City on Saturday to tape a 90-second segment on “Saturday Night Live” in a last-ditch effort to lure younger voters who don’t know much about her but tend to vote for Democrats. The move forced NBC to comply with Federal Communications Commission regulations and give Mr. Trump 90 seconds of free airtime, which he used to deliver an appeal during “Sunday Night Football” and NASCAR.

On Monday, high fences were erected around the U.S. Capitol and the White House to head off rioting after what is poised to be a divisive victory, no matter who wins.