Former El Paso Congressman Beto O’Rourke, the Texas upstart who seized the nation’s attention in an audaciously close Senate run against conservative icon Ted Cruz, announced Thursday that he will jump into the 2020 presidential race.

Reigniting the social media swirl of his 2018 Senate campaign, O’Rourke launched his run in a video on Facebook, Twitter and other digital platforms, setting up a series of weekend events in the first-in-the-nation caucus state of Iowa, where he is traveling.

“This is a defining moment of truth for this country and for every single one of us,” O’Rourke said in the early morning video, shot beside his wife Amy in a living room in El Paso. “The challenges that we face right now, the interconnected crises in our economy, our democracy and our climate have never been greater. … They will either consume us, or they will afford us the greatest opportunity to unleash the genius of the United States of America.”

A Texas kickoff rally is scheduled for March 30 in El Paso.

The long-anticipated announcement adds O’Rourke to a crowded field of Democrats vying to take on President Donald Trump, with whom he has repeatedly clashed over the administration’s hardline policies on border security, asylum and immigration.

Running on his identity as a lifelong resident of Texas’ heavily Hispanic border region, the El Paso native could be a leading Democratic voice on immigration, an issue that Trump made the centerpiece of his 2016 campaign with his promise to build a wall spanning the U.S. border with Mexico.

No issue defines O’Rourke more than his passionate opposition to Trump’s insistence on wall funding, which continues to be the central divide between the White House and Democratic leaders in Congress.

O’Rourke’s late decision to run for president — one that the 46-year-old father of three agonized over for months — could reshape the Democratic primary contest as well as the 2020 Senate race in Texas, where he was viewed as the most potent threat to three-term Republican incumbent John Cornyn.

Cornyn, portraying O’Rourke as an acolyte of Senate Democratic Leader Chuck Schumer, already had begun fundraising on the specter of an O’Rourke challenge, launching a “stop Beto fund.”

Vast following

O’Rourke’s more immediate challenge will be setting himself apart from a left-leaning field of Democrats —including Democratic Socialist Bernie Sanders — who have been raising money and campaigning for weeks in the early voting states of Iowa, New Hampshire and South Carolina.

In contrast, O’Rourke has drawn widespread attention for a solo road trip out West, which was variously praised as an authentic quest of personal discovery and ridiculed as an exercise in privilege and self-indulgence.

As he did in his surprisingly close loss to Cruz, O’Rourke signaled that the fuel for his presidential campaign will be grassroots organizing, small-dollar donations, social media savvy, and a personal charisma that supporters liken to Bobby Kennedy or Barack Obama.

“This is going to be a positive campaign,” he said, promising to revive a campaign spirit “that seeks to unite a very divided country.” In a nod to his Senate campaign, he added: “We saw the power of this in Texas.”

He also will start with a vast online following of supporters who contributed a record $80 million to his ultimately quixotic effort to topple Cruz, a pariah of the Democratic left. But unlike in his Senate campaign — highlighted by appearances with Texas music legend Willie Nelson — O’Rourke will now face a Democratic primary electorate divided between more than a dozen contenders, many with their own claims on activists’ affections.

Many still are awaiting the decision of former Vice President Joe Biden, who could instantly be considered the Democratic frontrunner.

While the list of contenders grows, some analysts see O’Rourke as a unique political figure from the American West who could widen the traditional Democratic coalition.

“The number of people interested and prepared to be active in the Democratic primary expands,” said Texas Democratic strategist Matt Angle of the Lone Star Project. “He’s one of those people who creates interest in politics and public policy in people who otherwise are just watching.”

O’Rourke would also be one of the youngest hopefuls in the Democratic primaries, part of a “Generation X” cohort that came of age after President Ronald Reagan and matured to adulthood under President Bill Clinton, the first baby boomer president.

His backers are already focusing on millennials and other young voters. “We’re investing heavily in students because they make up such a significant portion of Beto’s base and turning them out in 2020 will be essential in both the primary and general elections,” said Nate Lerner, co-founder of DraftBeto.org, one of two national groups that have been encouraging him to run.

A former punk band guitarist and tech company founder, O’Rourke has blended youthful idealism with an entrepreneurial streak and an ardent commitment to the bi-cultural heritage of his home town, which is 80 percent Latino.

A fluent Spanish speaker, O’Rourke made El Paso’s close relationship to cross-border Ciudad Juarez amajor theme of his Senate campaign, which celebrated migration as cultural and economic asset for Texas and the nation.

“If immigration is a problem,” O’Rourke said in his announcement, “it is the best possible problem for this nation to have.”

Cruz and other GOP critics dismissed his sunny vision as vague and “too liberal for Texas.” Cruz attacked O’Rourke for defending NFL players who knelt for the national anthem and for saying he was open to abolishing Immigration and Customs Enforcement, a statement O’Rourke ultimately walked back.

But amid the attacks, “Betomania” spread on social media from Texas to both coasts, along with the accompanying campaign cash and email lists, the lifeblood of 21st century political campaigns.

“The precursor of getting an online donation is having email addresses and having a previous online relationship with those people,” said Texas Democratic strategist Colin Strother. “Beto has that to the tune of close to $100 million.”

Inspiring, bucks tradition

While Trump has branded O’Rourke as aloser for his Senate race defeat, he energized Democrats across the nation with a campaign that brought them closer to a statewide victory in the Lone Star State than any Democrat in a generation.

The race raised his national profile and established him as a bursting star in the Democratic constellation, seizing the imagination of an activist base looking for a new generational voice.

“How many candidates running are truly inspiring?” said Ed Espinoza, who runs the left-leaning group Progress Texas. “Where is the Obama, the Howard Dean, the Bill Clinton of this race? There’s room for somebody who really inspires people. He really brings that to this race.”

The Democratic base will have to take the measure of O’Rourke against Democratic Sens. Kamala Harris of California and Elizabeth Warren of Massachusetts, two leading contenders who, along with Sanders, have shown energy, drive and passion.

O’Rourke’s entry in the race also could elevate the stakes in the Texas Democratic primaries, where he and former San Antonio Mayor and HUD Secretary Julian Castro could be vying for native son status.

Meanwhile, O’Rourke’s unconventional campaign style continues to be questioned by friends and critics alike. Repudiating consultants, pollsters and PAC money, he relies on “showing up,” spreading his message on social media, word-of-mouth, and grassroots energy.

Even some sympathetic strategists have questioned whether he can replicate that style on a national scale. But he also has won praise for a hip, disheveled look of sweaty shirts and a willingness to drop f-bombs amid young, enthusiastic audiences.

“He’s areal person,” Strother said. “He’s not a cookie-cutter candidate. He speaks off-the-cuff and from the heart. Therefore, he doesn’t always say everything perfectly.”

While O’Rourke’s support within the Democratic base could overlap with that of Sanders, he is not as closely associated with the Vermont senators’ push for a “Medicare for All,” a term that Republicans liken to socialism. O’Rourke has embraced the goal of “universal health care,” but says he’s open on how to achieve it. He also was a superdelegate for Hillary Clinton in 2016 and has described himself as a committed capitalist in the search for market solutions to problems like climate change.

Despite their differences, some analysts say O’Rourke’s candidacy could siphon off support from the cadres of fervent anti-establishment activists who made Sanders the runner-up to Clinton in 2016. “I think Bernie’s lane without question has narrowed,” Angle said. “So it opens up not just for Beto, but for other people.”

‘Moment of peril, promise’

In some respects, O’Rourke’s signature opposition to a wall — he has even talked about taking down some barriers around El Paso — could position him as the Democrat who presents the starkest contrast to Trump. Immigration and border security are also the ground where Trump prefers to campaign.

Wherever the fight is joined, O’Rourke will be expected to be Trump’s antithesis in both style and substance. “The most important thing for Democrats,” Angle said, “is to make sure this race is about Donald Trump.”

In his announcement video Thursday, O’Rourke left little doubt that he will present a stark contrast to a president many Democrats see as a danger to American democracy.

“This moment of peril,” O’Rourke said, “produces perhaps the greatest moment of promise for this country and for everyone inside it.’’

Asked if he had seen that O’Rourke had joined the race on Thursday, Trump responded: “I think he’s got a lot of hand movement. I’ve never seen so much hand movement. Isaid ‘is he crazy or is that just the way he acts?’ ”

Trump said he’s ready to take on anyone the Democrats choose: “Whoever it is, it makes no difference to me whatsoever.”

Jeremy Wallace contributed to this report. kevin.diaz@chron.com