President Trump will leave the White House with a massive social media following that he could use to shape the nation’s politics throughout his successor’s administration and beyond.

When Trump started his first campaign in 2015, he had just 3 million Twitter followers and 10 million on Facebook. But should Democrat Joe Biden’s apparent electoral edge withstand legal challenge, Trump would leave office with a singularly powerful online megaphone — at least 88 million followers on Twitter, 31 million on Facebook and 23 million on Instagram — that will give him a unique ability to communicate his thoughts to legions of supporters accustomed to hearing from him more than three-dozen times a day.

It’s a pace he could easily keep up as a private citizen looking to influence debates, mock opponents or help revive his flagging business interests, social media researchers say.

This power, honed and enhanced through two national campaigns and nearly four years as president, gives Trump the opportunity to do something rarely attempted by the men who previously held the nation’s highest office — keep the national gaze fixed on himself as a new chief executive tries to command the national stage. It’s something that could complicate Biden’s stated goal of reunifying a nation fractured across regional, racial and partisan lines.

“There’s no way that Donald Trump sits on his hands while Biden undermines his legacy,” said Timothy Naftali, a New York University historian. “He is likely to be a fundamentally disruptive presence in American political life as an ex-president. And that is, once again, norm busting.”

Trump also could remain a potent force for misinformation by continuing to undermine the election’s legitimacy and sow doubt about the results in the minds of millions of people, researchers said. He has repeatedly railed against mail ballots and other elements of the national vote, making unfounded claims he has pressed with ever greater intensity as Biden mounted an apparent comeback in recent days.

Trump did not concede Saturday, tweeting “I WON THIS ELECTION, BY A LOT!” at 10:36 a.m., about two hours before CNN and other news outlets called Pennsylvania for Biden.

In the days after the election, Trump’s allies turned to Facebook, Twitter, YouTube and other social media platforms to echo and amplify these claims, often peddling misleading videos and other supposed evidence that independent fact-checkers have deemed false, prompting numerous actions by technology companies to label or remove the misleading claims.

Despite frequent complaints by Trump and his allies that technology companies are biased against him, the day after the election he had five of the 10 Facebook posts with the most English-language interactions — a category that includes retweets, likes and other user actions — according to data from CrowdTangle, an analytics tool.

His tweets, more than 32,000 and counting since he formally entered politics, continue to shape the news cycle, even as they increasingly get slapped with warning labels for violating Twitter policies against misinformation. Trump’s misleading election night tweet claiming he had a “big win,” well before the election was decided, for example, got 125,000 retweets before Twitter restricted it. Twitter also labeled his Saturday morning tweet.

Trump may prove easier to ignore as a former president, at least by those who dislike his politics or his bombastic, truth-bending style. But judging by ballots cast in this election, the president’s base of support is roughly 70 million Americans — a group so large that, if taken by themselves, would exceed the population of the United Kingdom, the world’s 21st largest country.

“Whenever Trump leaves, he will leave with the biggest direct-to-supporter communications infrastructure in modern politics,” said Philip N. Howard, director of the Oxford Internet Institute. “He’ll be able to keep his supporters in an information bubble for an extended period well beyond the end of his public office. And he’ll have a loyal and adoring audience for his political heckling and product placement — the ultimate distribution network for conspiracy, sensationalism, extremism and polarization.”

The nation’s first president, George Washington, set a standard of nonintervention by stepping down after two terms and retiring to his Northern Virginia plantation, Mount Vernon, despite growing rancor among his fellow Founding Fathers.

Many presidents have since taken more visible and vocal roles after leaving office, Naftali said. Theodore Roosevelt, for example, soured on his handpicked successor, William Howard Taft, and started his own political party. Roosevelt then ran unsuccessfully again for the presidency, in 1912, four years after initially stepping down.

But recent decades — in an era during which the power of television has made presidents akin to celebrities capable of reaching most of the nation with an immediacy once impossible — have seen former presidents of both parties largely step away from the political spotlight after leaving the White House.

Trump’s predecessor, Barack Obama, didn’t even open his own Twitter account until his second term but eventually built an even larger Twitter following than Trump’s, accumulating 125 million followers. But Obama largely held his tongue on partisan politics until recent months, as this year’s presidential campaign quickened. And Obama has never tweeted with anything close to the frequency or impact of Trump.

Trump’s ability to command attention goes far beyond the mere numbers of followers he has on various platforms. Even his detractors agree the president has a rare skill at using Twitter to drive conversation with posts that are often harsh — even inflammatory — but hard to ignore. His rapid-fire style, complete with frequent capitalizations and the occasional spelling error, makes his voice hard to tune out.

Trump also benefits from the unrivaled enthusiasm of his followers, many of whom share his messages instantaneously by using software to automatically retweet him, researchers have found. Some use his Twitter feed as a primary source of their news, akin to having the television always on in the background, said Claire Wardle, U.S. director of First Draft, a nonprofit organization focused on addressing misinformation and disinformation.

“The networked infrastructure that the Internet allows, he has capitalized on that in an extraordinary way,” Wardle said. “He has his megaphone, but he also has this network that takes his messages and distributes it in their own communities.”

She pointed out that before the 2016 election, Trump had conversations with TV networks about having his own show. “But today he doesn’t need Trump TV when he has the most powerful communication network at his fingertips,” Wardle said.

When he leaves the White House, Trump will lose the extra leeway that Twitter affords world leaders, and Facebook may stop bending its policies to soothe criticisms from the president and his political allies. But even when that deference disappears, Trump will retain the ability to turn up the volume on his claims, even if he may have to become more cautious about how he makes them.

He has used his time in office effectively to grow his follower base tremendously. Trump’s median number of retweets, which was 66 the month before announcing his candidacy in June 2015, has soared by nearly 30,000 percent, to 19,600 last month, said Darren Linvill, a social media researcher at Clemson University.

Trump and his campaign also built a formidable email list, with tens of millions of valuable names and email addresses, during his time as a politician. The Trump campaign has sent out more than 460 million emails seeking donations to support its legal fight related to the election since Tuesday, according to data compiled by Trevor Davis, chief executive of CounterAction, a D.C.-based digital intelligence firm. He said other politicians have used such lists to raise money for other candidates and exert influence after leaving office.

“An email list is a source of political power,” Davis said.

Trump also has developed an echo chamber of supporters throughout the social media universe, including influential conservatives and countless ordinary supporters who respond to his messages and contend that hostility from mainstream news sources and tech companies could prevent his voice from being heard. An elaborate, well-developed network of far-right groups, such as the violent all-male Proud Boys and supporters of conspiracy theories such as QAnon, revere Trump and work to amplify what he says, online and off.

One critical test of whether Trump’s megaphone will be as potent after he leaves office will be whether he can forge the same close alliance with Fox News that he enjoyed during his presidency, said Yochai Benkler, co-director of the Berkman Klein Center for Internet & Society at Harvard University and an expert on the news media and misinformation. Fox pundits have consistently repeated White House talking points, as has the news side of Fox, Benkler said, giving significant credence to and amplification of Trump’s messages.

Another issue will be whether Trump tries to capitalize financially on his audience in the months ahead, Benkler said. He suggested Trump could go into competition with Fox if he doesn’t regain the same level of support following a bruising election in which the president and his allies criticized the network for its polling and its election-week declarations about which states had been won by Biden.

So far, he said, the news network has shown “restraint,” in its coverage of the Trump campaign’s allegations of voter fraud and attempts by Democrats to steal the election. “But I’m not sure it will hold,” he said.