For now, after decades of disappointment, Texas Democrats are excited about the potential of sending two of their own to the national political stage. "This is a sea change," said Garry Mauro, who was Texas director for Hillary Clinton's 2016 presidential campaign. "We have two candidates with star quality."
The two men have taken different approaches to the White House buzz. Castro, a secretary of Housing and Urban Development under former President Barack Obama, has taken a methodical approach. He's paid visits to the early voting states of Iowa and New Hampshire and campaigned around the country for top Democrats ahead of the midterms. His new book, "An Unlikely Journey," details his rise as the son of a Latina activist single mother to political heights, including being the keynote speaker at the 2012 Democratic National Convention.
Arthur Schechter, a prominent Houston Democratic fundraiser, said he first spoke to Castro about a 2020 bid weeks ago and that he and his brother are "both very ambitious and there's nothing wrong with that."
Castro has spent years studying to improve his Spanish skills and could be a strong contender for Hispanic voters, telling The Associated Press in a recent interview, "Part of my vision for the future of the party is to take the 78 electoral votes of Arizona, Texas and Florida," all of which Trump carried in 2016 and have booming Hispanic populations.
O'Rourke, meanwhile, rocketed into the 2020 conversation almost overnight after coming within three percentage points of defeating Republican Sen. Ted Cruz. He's done little to build the groundwork for a presidential run and hasn't contacted many top Texas donors. But his national profile is strong after raising more than $60 million for his Senate campaign — much of it from small donations — and coming close to unseating Cruz. He's increasingly discussed as someone who could attract the same type of attention — and financial resources — as better established Democrats such as former Vice President Joe Biden and Sens. Cory Booker of New Jersey, Elizabeth Warren of Massachusetts and Kamala Harris of California.
"He's in the top tier for sure. We saw Beto yard signs in Iowa. We have bumper stickers," said Sean Bagniewski, chairman of Iowa's Polk County Democratic Party, which recently invited O'Rourke and other top Democrats to visit the state. "He's the only candidate that has that kind of enthusiasm at this point."
O'Rourke said Monday that he prefers to finish his congressional term Jan. 3 before deciding what's next. But that's a far cry from repeatedly saying during the Senate campaign that he had no White House aspirations whatsoever.
So far, there aren't signs of animosity between the Texans. Castro campaigned with O'Rourke during his Senate run. He and his twin brother, Joaquin, a congressman from San Antonio, attended O'Rourke's Election Night rally.
But O'Rourke has already eclipsed Castro's national profile and, if he runs, may easily overshadow him. Castro insists he won't be deterred by O'Rourke or other potential competitors, saying "I'm going to run regardless of what anyone else does."
Intrastate clashes aside, a potential O'Rourke run could be especially challenging to Castro. Though the congressman is not Hispanic, he speaks fluent Spanish and champions his hometown of El Paso, on the Texas-Mexico border. Mustafa Tameez, a Houston strategist connected to top Democratic donors, said O'Rourke may trail Castro and other potential 2020 hopefuls in early preparations, but can catch up quickly.
"He created almost a million people that contributed to him," Tameez said. "He can send out one email and raise more money than most established, seasoned veteran politicians and their bundlers." Both Castro brothers also sat out the 2018 cycle rather than try for a statewide office. At the time, avoiding what looked like a sure loss seemed bound to bolster a possible 2020 presidential bid. But jumping into a seemingly unwinnable race paid off for O'Rourke, laying bare the perils of being overly cautious rather than seeking out momentum in unlikely places.
The last Texas Democrat to run for president was Lloyd Bentsen in 1978. Republican George W. Bush went from the governor's mansion in Austin to the White House in 2000 and fellow Texans Rick Perry, Ron Paul and Cruz have all made presidential bids since.
Some see O'Rourke's strength this year as proof that Democratic hopes in Texas aren't totally lost and, one day, the party could seriously vie for the state's 36 electoral votes and choke off any viable Electoral College path to the presidency for Republicans.
"Since 1968, the dream deferred for the Democratic Party has been to win back Texas," Bagniewski said. "We're getting closer and closer every time. Beto showed us it could really happen in our lifetime."