Video of the candidate defending NFL players' right to protest during the national anthem had been viewed by millions even before NBA star LeBron James called it a "must-watch." Another of O'Rourke, a three-term congressman, thrashing through a Whataburger parking lot on a skateboard is almost as popular, increasing the onetime punk rocker's already considerable street cred.

National magazines are suggesting he could be a Democratic vice-presidential pick in 2020 — or even a White House contender, ala a young Barack Obama. Sure, O'Rourke may lose to incumbent Republican Sen. Ted Cruz, the argument goes, but just staying competitive in Texas, which hasn't elected a Democrat to statewide office in nearly a quarter century, would still further boost his political star.

The White House is taking notice. President Donald Trump tweeted that he plans to stage "a major rally" for Cruz in October. Help from the president was long unthinkable in a race that for months looked like a Cruz cakewalk.

The hype machine powering O'Rourke has brought in piles of campaign cash and generated excitement nationally. But it also risks eventual backlash. Voters have often punished candidates for getting too big for their political britches — especially if they haven't won anything yet. O'Rourke need only look to his opponent for an example of a politician whose ambitions irked voters he needed.

Still, the Democrat seems eager to test a Trump-era theory that, with such an outsized personality in the White House, voters may no longer want their politicians to stay humble.

O'Rourke has largely welcomed the spotlight. His stance on anthem protests landed him an appearance on Ellen DeGeneres' TV show this week. O'Rourke also hasn't disavowed descriptions of himself as "Kennedy-esque," given his boyish good looks. He livestreams constantly and, in March, when he appeared on HBO's "Real Time with Bill Maher," the crowd in Los Angeles cheered so much that the host crowed, "It's like when the Beatles came to America."

"You can't control it," O'Rourke spokesman Chris Evans said of the attention. He disputed the idea that national praise could hurt back home, saying it's "hard to say we're not focused on Texas" since O'Rourke just spent 34 days of the congressional summer recess campaigning without leaving the state.

O'Rourke himself has shrugged off questions about whether too much attention could create unrealistic expectations. "The whole thing is not something he's talked about, really," Evans said.

Some Texans think the campaign might want to, though.

"Most voters in Texas still don't know who Beto O'Rourke is. If the first thing they know about him is he's like Obama, then that's going to turn off more voters than it attracts," said Brandon Rottinghaus, a political science professor at the University of Houston.

Ironically, O'Rourke could ask Cruz about this problem. He arrived in the Senate and immediately laid the groundwork for a presidential campaign that saw him finish second to Trump in the 2016 primary. Cruz then alienated much of his base by refusing to endorse Trump at that year's Republican National Convention, and though he's since embraced the president, some Texas conservatives say they're still wary, seeing what happened at the convention as putting personal ambition over party.

Florida Republican Sen. Marco Rubio has also run into issues with political ambition clashing with his day job, and just ask former North Carolina Democratic Sen. John Edwards, who was already fading before word of his affair and a child with his mistress broke, about how well being dubbed the second coming of Bill Clinton went.

Texas Democrats, meanwhile, have been down this road before. Wendy Davis staged a marathon state Legislature filibuster in the name of abortion rights, rocketed to national stardom and launched a 2014 gubernatorial bid. Like O'Rourke, Davis was a strong fundraiser and the toast of liberals from Hollywood to Brooklyn. Largely unable to define herself beyond abortion, which resonated nationally but not at home, Davis eventually lost by 20-plus points to Republican Gov. Greg Abbott.