Beto O’Rourke has already used his once-longshot Texas Senate run to become a national Democratic phenomenon, shatter fundraising records and set off whispers that he could be a credible 2020 White House contender.

But will it be enough to upset — or even stay close to — incumbent Republican Ted Cruz in a state as deeply conservative as Texas?

The two candidates square off Tuesday in their hard-fought race that could help determine control of the Senate. Both say strong early voting statewide is a good sign for them. Early voting in the state’s 30 largest counties alone already exceeded the total number of ballots cast during the 2014 midterm elections in Texas.

A three-term House member and onetime member of a punk rock band, O’Rourke was virtually unknown outside his Texas-Mexico border hometown of El Paso before announcing in March 2017 that he was taking on a seemingly unwinnable race against Cruz. A Democrat hasn’t won a Texas Senate seat since 1988, and no one from the party has captured any statewide office since 1994, the nation’s longest political losing streak.

But O’Rourke visited all 254 Texas counties and often drew larger-than-expected crowds, even in fiercely conservative areas. Preaching optimism and bipartisanship, he also refused to soften a liberal agenda that included calling for impeaching President Donald Trump, decriminalizing marijuana, implementing universal health care and gun control and relaxing federal immigration policies.

“My confidence is in the people of Texas,” O’Rourke told reporters on Monday night, moments before staging a raucous rally with Mariachi band at the University of Texas at El Paso, mere blocks from his home. “I think we have every indication, based on turnout so far, that we’re going to have a very good day tomorrow.”

Cruz scoffs at the notion that O’Rourke could beat him. Still, late summer polls showed the challenger within striking distance. Though more recent ones indicate that the senator has regained his footing and maintained a modest lead, the race has gone from cakewalk to far closer than expected.

Even that was a shock for Cruz, who won 10-plus contests during the 2016 Republican presidential primary and has long been considered the most powerful and popular conservative in a state full of them. But the battle with O’Rourke proved that many Texas conservatives remained angry after Cruz clashed bitterly with Trump in 2016 and refused to endorse him during the Republican National Convention. Though the senator has since become one of Trump’s staunchest defenders, the president nonetheless staged a massive rally in Houston just two weeks before Election Day to ensure his conservative base wouldn’t abandon Cruz.

“It’s the time for choosing. It’s the time for action. We know that the hard-left right now, they’re angry. They’re energized,” Cruz said Monday. “They’re filled with rage and hatred for the president. And that’s dangerous.”

As Cruz has embraced the White House, O’Rourke has concentrated on mobilizing young voters, Texans living along the U.S.-Mexico border and people who moved to the state from elsewhere.

No matter what happens, O’Rourke is now a national Democratic star, using donations from across the nation to smash Senate race fundraising records — including raking in more than $38 million in the three-month period from July through September alone. He insists he won’t run for any office higher than Senate, but that’s done little to quash speculation that he could challenge Trump for the presidency in two years.

Cruz, who has made no secret about wanting to run for president again once Trump leaves office, even gleefully tweeted national polls showing O’Rourke cracking the top 10 among potential Democratic White House hopefuls in 2020, arguing they show how liberal he is.

(AP)