In speeches, social media posts, and interviews, former President Donald Trump has been signaling that he is highly likely to challenge the election results should he lose on Tuesday. The big question is what may happen next.

Mr. Trump never conceded his 2020 loss, and his extralegal attempts to overturn that election culminated in the Jan. 6, 2021, U.S. Capitol riot. In this campaign, he has again refused to say he’ll accept the results if he comes up short, and is already making misleading claims that the vote is being rigged against him.

“They’re going to cheat. They cheat. That’s all they want to do is cheat,” Mr. Trump said at a Wisconsin rally in early October. “It’s the only way they’re going to win.”

Why We Wrote This

Since former President Donald Trump’s extralegal efforts to overturn his 2020 defeat, the system has been strengthened in a variety of ways. But a narrow victory by Vice President Kamala Harris could still lead to a drawn-out battle.

Mr. Trump’s team has been preparing for this moment for four years, organizing on the ground and installing allies on county election boards. The Republican National Committee has invested heavily in “election integrity” efforts, training thousands of volunteers to watch for potential fraud. Trump-aligned groups have proliferated across the country to challenge election results, including a network organized by Cleta Mitchell, who worked with Mr. Trump to try to overturn his 2020 loss. Lawsuits are being filed at a historically high rate, with more legal wrangling a near-certainty. There have already been isolated incidents of campaign-related violence, intimidation, and ballot sabotage.

Vice President Kamala Harris’ campaign is also gearing up for a post-election battle. Ms. Harris told ABC News that her team was “sadly ready” to respond should Mr. Trump try to overturn the results.

Yet while post-election chaos is quite possible, 2024 is unlikely to be an exact replay of 2020. In important ways, the system has been strengthened: Congress passed legislation making clear that elected officials cannot reject the will of the voters. And states and localities have worked assiduously to harden the voting process against potential attacks. Mr. Trump also doesn’t have control over the military or Justice Department this time around, and it will be Vice President Harris, not Vice President Mike Pence, presiding over the next Electoral College count in Congress.

If the election is close, we’ll likely see “lots of litigation,” as well as “various efforts to challenge the legitimacy of the outcome,” says Rick Pildes, a constitutional law professor at New York University. Still, he adds, “I think there are many institutional, legal, and even political safeguards in place that should ensure that the lawful winner of the election actually becomes president.”

What’s changed since 2020

Many Americans expect Mr. Trump to reject an election loss. Two-thirds of swing-state voters in a Washington Post poll released last week said they doubt the former president will accept the result if he loses this election – including more than one-third of those who plan to vote for him. A majority of swing-state voters, 57%, also said they feared Mr. Trump’s supporters would respond to a loss with violence.

Mr. Trump set off alarm bells among Democrats recently when he declared that he and House Speaker Mike Johnson had a “little secret” that could help him win – a comment many took as a hint the House might try to overturn a Harris win. Mr. Johnson said the next day that the secret was simply “one of our tactics on get-out-the-vote,” not anything “diabolical.”

Even if House Republicans wanted to, though, it’s unlikely they could block a legitimate win by Ms. Harris, thanks to a new law Congress passed in 2022. The Electoral Count Reform Act (ECRA) made clear that the “alternate elector” legal theory cited by Mr. Trump’s allies to try to overturn his loss in 2020 – appointing rogue slates of Electoral College electors who would back him over Joe Biden – would be a legal no-go in future elections. It would take majorities in both chambers of Congress to reject the law’s strictures on certification – and many Senate Republicans who backed the law will still be in office on Jan. 6, 2025, making that an unlikely outcome.

“The good news is that ECRA is a really big improvement,” says Ned Foley, a constitutional and election law expert at the Ohio State University who advised Senate negotiators who crafted the law. “The whole approach of ECRA is to basically say that the rule of law controls the outcome, and that politicians can’t subvert the outcome just because they don’t like it.”

Democrats and Republicans who have stood up to Mr. Trump currently hold the governorships and secretary of state offices in nearly every swing state – many having defeated candidates Mr. Trump endorsed in the 2022 midterms. That means the officials who are supervising the elections and who will ultimately certify the statewide results are unlikely to side with Mr. Trump if he tries to subvert the law.

The biggest risk may come if county officials refuse to certify their results. Trump supporters have attempted this in other elections in recent months, arguing that the votes had problems in their view and should be tossed out. But ECRA as well as many state laws have underscored that the certification of election results isn’t at the discretion of local officials. They would likely face judicial orders to certify, or face real legal penalties – a strong motivator, though no guarantee.

Georgia Secretary of State Brad Raffensperger, one of the Republican officials who resisted Mr. Trump’s demands to overturn his state’s results in 2020, told the Monitor in late September that county officials would be forced to follow the law and certify their results, whichever candidate benefitted.

“At the end of the day, state law is very clear, and that cannot be violated. All elections must be certified,” he said. “That’s black-letter law, and everyone has to follow state law.”

A 2023 U.S. Supreme Court ruling also rejected a Republican-pushed “independent state legislature” legal theory that would have given dramatically more power to state legislatures to set rules for federal elections. That decision lowered the chances that GOP-controlled state legislatures could successfully overturn the will of the voters should Ms. Harris win in their state.

History rhyming, not repeating itself

But while there are more safeguards around the election process than in 2020, a more fraught situation could still develop if the margin of victory is narrower.

The 2020 election wasn’t actually that close. All but one of the swing states went for Mr. Biden, who ultimately got 306 electoral votes, far more than the 270 needed for victory. That meant Mr. Trump needed not just one but several states to overturn their results, and his potential allies in any given state weren’t guaranteed success even if they went along with his efforts.

No individual state was close enough to give a legal challenge much of a chance, either. Recounts and court fights can swing election results, but it’s almost unheard of for a state’s results to change if the margin of victory is more than around 1,000 votes. The narrowest margin in 2020 was in Arizona, which went for Mr. Biden by just over 10,000 votes.

A closer vote count, however, could lead to a drawn-out court battle. The 2000 election, which came down to just 537 votes in Florida, was fought in the courts and ultimately settled in a controversial decision by the U.S. Supreme Court.

This year, it’s clear both sides are particularly ready for a courtroom brawl. Dozens of legal battles are already underway:

On Saturday, Trump’s team filed a lawsuit falsely claiming that several Georgia counties were breaking the law by letting voters drop off ballots – only to have a judge immediately rule against them.

Friday evening, the U.S. Supreme Court dismissed a request from Republicans to overturn a Pennsylvania Supreme Court ruling allowing voters who messed up their mail ballots to be able to cast provisional ballots on Election Day.

The Trump campaign sued after officials in Bucks County, Pennsylvania closed in-person absentee voting too early; a judge extended the deadline as a result.

Democrats are currently suing in Erie County, Pennsylvania over mail ballot delays.

Republicans have lost last-minute suits in multiple states seeking to tighten rules around military and overseas ballots.

While the conservative-dominated U.S. Supreme Court rejected a number of last-ditch attempts to overturn Mr. Trump’s loss in 2020, that doesn’t mean they’d do so again in different circumstances.

Democrats and voting rights advocates were alarmed last week, when the high court’s conservatives ruled that Virginia could restart a purge of 1,600 voter registrations suspected of being non-citizens. The court overturned a unanimous lower court decision that had blocked the effort because it fell in the 90-day pre-election “quiet period” in which federal law prohibits removing voters from the rolls – and because multiple U.S. citizens were found to have been erroneously flagged for removal.

Democrats also worry about what the court might do if Republican-controlled state legislatures decide to throw out narrow wins by Ms. Harris and instead send alternate elector slates to Congress, something Mr. Trump tried and failed to get them to do four years ago. That is now prohibited under ECRA – but that brand-new law hasn’t been tested in court.

Isolated incidents of sabotage, disruption

For all the chaos of the 2020 post-election period, Election Day itself went off fairly smoothly. This year, while early voting has been mostly trouble-free, there have been a handful of alarming, if isolated, incidents of illegal election disruption.

In Oregon and Washington, someone set fire to a pair of ballot drop boxes, destroying hundreds of ballots (footage obtained by police shows the same car at both sites). In a separate, earlier incident, someone set fire to the contents of a mailbox in Arizona, damaging a handful of ballots.

In Florida, Police arrested an 18-year-old Trump supporter for brandishing a machete at a polling location last week. More than a dozen other cases of election-related violence, intimidation, and sabotage have been identified in recent weeks.

The FBI and Department of Homeland Security warned in a bulletin sent to state officials earlier this month that “election-related grievances” could motivate people to “engage in violence, as we saw during the 2020 election cycle.”

“It does appear as if the Trump campaign and his allies right now are spending more time trying to create a false myth of the inevitability of his victory,” says David Becker, a former Justice Department official who runs the nonpartisan Center for Election Innovation and Research. “I’m worried about how that could be leveraged post-election, should Trump lose, to create a sense of shock and anger that could result in violence post-election.”