A resurgent Joe Biden used a come-from-behind surge in Texas and throughout the American South to further cement the race for the Democratic nomination for president as a two-person battle.

Unofficial results have Biden beating Vermont Sen. Bernie Sanders in Texas, thanks in large part to a dramatic turnabout on election day. During early voting, Sanders held a narrow lead. But on Tuesday, voters in Texas overwhelmingly shifted to Biden.

After his weekend victory in South Carolina, Biden was hoping to carry the momentum over to Texas where he held two big rallies on Monday and gained key endorsements, including from former presidential contender Beto O’Rourke.

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As the Associated Press called the race for Biden at 1 a.m., it was clear that Biden had a major reversal of fortune over the last few days, particularly in Harris County, the state’s most populous county.

Biden on Tuesday credited O’Rourke for helping him in Texas on election day — and securing the biggest share of the state's 228 delegates.

“We’re doing well in Texas because of Beto O’Rourke,” Biden told his supporters during a speech in Los Angeles, as the votes were tallied.

Sanders, meanwhile, was making a strong showing in California, with its 415 delegates, after winning in Colorado, Utah, and his home state of Vermont.

Still, Sanders and Biden are the clear winners of Super Tuesday, as 14 states voted. Biden posted a big win in Virginia where suburban demographics in some areas mirror those in Texas suburbs that have fueled Democratic optimism here for 2020. Biden also won Massachusetts — the home state of Sen. Elizabeth Warren — as well as North Carolina and Arkansas.

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Early voting in Texas bolstered Sanders, particularly in Austin, San Antonio, Laredo and along the Rio Grande Valley to help him contend with Biden, who did best in Harris County and Dallas County.

The clash between Biden and Sanders, each leading coalitions of disparate demographics and political beliefs, peaked on a day that could determine whether the Democratic battle will stretch all the way to the July convention or be decided much sooner.

The former vice president and the three-term senator took aim at each other from dueling victory speeches separated by 2,500 miles (4,000 kilometers) Tuesday night.

“People are talking about a revolution. We started a movement,” Biden charged in Los Angeles, knocking one of Sanders’ signature lines.

And without citing his surging rival by name, Sanders swiped at Biden from a victory speech in Burlington, Vermont.

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“You cannot beat Trump with the same-old, same-old kind of politics,” Sanders declared, ticking down a list of past policy differences with Biden on Social Security, trade and military force. “This will become a contrast in ideas.”

Texas was a major disappointment for former New York City Mayor Mike Bloomberg, who bet big on the state, sinking $57 million into TV ads and visiting Texas seven times since his campaign began in late November. But statewide, Bloomberg was back in third place behind both Biden and Sanders.

Speaking in Florida, Bloomberg gave no hint that he was reconsidering his campaign after not winning any Super Tuesday states he invested in.

“Our campaign is a fight for America’s ideals and values," Bloomberg said. "It’s a fight to build a better future, for everyone — not to bring back a past that left so many out. It’s a fight we cannot afford to lose. So I need your help — and I need your vote. "

It was shaping up as an even more disappointing evening for Elizabeth Warren, a former Texas resident who graduated from the University of Houston in 1970. She leaned on former San Antonio Mayor Julián Castro in the closing weeks of the race to help her here.

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Still, Warren gave no signs of dropping out despite her poor showing in Texas and elsewhere. At a rally in Michigan as results were coming in, Warren implored the crowd to ignore pundits and people strategizing about how to vote.

"Here's my advice: cast a vote that will make you proud," she said. "Cast a vote from your heart and vote for the person you think will make the best president of the United States of America."

Over the last 8 days, Texas has been visited by Sanders, Warren, Bloomberg and Biden, all of whom held rallies down the stretch and made appearances in Houston in the final week.

For Biden, the final days were about shoring up votes in the black community in Houston. While speaking at a rally at Texas Southern University on Monday, he made clear his comeback in South Carolina was due to minority voters.

“I am very much alive because of you,” he said.

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That night, Biden traveled to Dallas picking up endorsements from O’Rourke, former South Bend Indiana Mayor Pete Buttigieg and U.S. Sen. Amy Klobuchar, who dropped out of the race just minutes before Biden spoke in Houston.

That appears to have helped Biden consolidate the vote among moderate Democrats in Texas.

Sanders a week earlier made stops in San Antonio and Houston to shore up his support, repeating his pledges to push for Medicare for All, a higher minumum wage and eliminate college debt.

While 14 states voted on Super Tuesday, Texas triggered outsized attention because its 228 delegates dwarf what most other states have to offer and public polling suggested it was anyone’s guess who would win.

This story contains material from the Associated Press.

jeremy.wallace@chron.com