Updated at 11:55 p.m. Wednesday with Cruz fundraising totals and comments.

WASHINGTON -- Democrat Beto O'Rourke raised an eye-popping $10.4 million in the last three months -- catching up to Sen. Ted Cruz's six-year haul in just over 15 months as he seeks to topple the darling of Texas Republicans.

The El Paso congressman's ability to vastly outpace the incumbent is no longer in doubt. Cruz collected $4.6 million during the same period, and O'Rourke has extended his streak of raising more than the incumbent in one of the nation's costliest races.

"It's a very positive sign for us that people in Texas believe in this campaign and are making it possible," O'Rourke said in an interview Wednesday. "At this pace we're raising more than we assumed, maybe even more than we imagined."

The latest three-month haul leaves O'Rourke with $14 million for the last four months before Election Day. His fund-raising total is now about $23.7 million. That's almost exactly the sum Cruz has raised for his Senate campaign account since winning the seat in 2012. But those are rounded numbers. Bragging rights will have to wait until the campaigns file their quarterly reports, which aren't due until Sunday.

Just before midnight on Wednesday, Cruz announced that he raised $4,591,872 from March to the end of June, bringing his total to $23.7 million, too, with $10.4 million in the bank.

"Sen. Cruz is deeply grateful to the Texans who support his policies and values of conservatism and constitutionalism," campaign spokesman Emily Miller said in a written statement.

Democrats have been gunning for years to end a generation of GOP dominance in Texas.

O'Rourke's torrid fund-raising reflects that and other factors: backlash against an ambitious senator who engineered a government shutdown and alienated many colleagues in his initial years in office, Texas' shifting demographics, Democrats' itch to bloody President Donald Trump and his allies, and O'Rourke's formidable charm and tireless approach to the effort.

In late July he'll embark on a 34-day driving tour of the state.

But Texas hasn't elected a Democrat statewide since 1994.

While candidates need plenty of cash to mount a successful bid in a state with 30 million people and 20 media markets, money guarantees nothing.

Cruz entered the race with universal name ID in Texas. He doesn't need to spend as much to introduce himself to voters in the far corners of the state. Plus, although Cruz has lagged so far, he's a proven fund-raising powerhouse in bids for the Senate and White House. And unlike O'Rourke, who has sworn off political action committee support, he'll be able to tap vast sums from wealthy backers.

It's hard to imagine GOP groups allowing Cruz to flail if there are signs of that. Polls have shown O'Rourke keeping the contest to single digits.

Both have shown prowess at attracting low-dollar donors in large numbers. It's relatively easy for campaigns to persuade someone who's already clicked a button to send in another $50, again and again.

O'Rourke announced his tally on Wednesday night in a Facebook Live with supporters.

"To do it in this way through small dollar contributions -- that's what democracy looks like," he said on his livestream. "That's how we get Texas back. That's how we doing something great for the country."

The donations came from 215,000 unique contributions, he told The Dallas Morning News hours earlier. "Ranged the gamut from 5 bucks to much higher than 5 bucks," he said.

Cruz comes to the race as one the best known political figures in America, both loved and reviled.

He's a tea party darling who catapulted onto the national stage with his victory over the GOP establishment in 2012, thrilling voters in Iowa and New Hampshire with a combative style that included engineering a government shutdown and prodding fellow Republicans to fight harder against Obamacare.

He leveraged the popularity among conservatives to run for president, running second to Trump.

Jennifer Duffy, who tracks Senate races for the nonpartisan Cook Political Report, is dubious that O'Rourke can overcome the obstacles even with a blistering pace of fund-raising. Cook rates the contest as "likely Republican," meaning it's potentially competitive, but not very. Other handicappers have a similar view of the race.

"I don't see it changing any time soon. It takes more than money to win a race," Duffy said.

Cruz raised $19.4 million since taking office, through the end of March. The Washington Examiner reported earlier this week that he raised about $4 million in the second quarter of 2018.

"Texans now see Democrat Rep. Beto O'Rourke wants open borders and gun control. He said he is `open to' abolishing the U.S. Immigration and Customs Enforcement (ICE) agency and would vote to impeach President Donald Trump," Miller, the Cruz spokeswoman, said late Wednesday. "In contrast, Sen. Cruz has spent the last six years successfully fighting for the issues that matter to Texans: promoting jobs, cutting taxes, reducing regulations, securing the border, expanding school choice and defending the Constitution."

Roughly 70 percent of O'Rourke's funds came from Texas donors at last check.

Variety reported that he was in Los Angeles on Monday to raise campaign cash for at least the third time, at an evening reception with tickets starting at $250. Republicans tweaked him for making the trek to Hollywood, although Cruz has likewise courted donors in California and around the country.

"Yeah, there are folks all over who understand that our shared future in this country is at stake. Texas has a great opportunity to lead the way," O'Rourke said. "I'm very grateful for the help that we're receiving from folks, even people outside of Texas."

As of late March, the Texas race ranked third for money raised by Senate candidates in the 2018 elections.

Massachusetts, where liberal Sen. Elizabeth Warren is seeking a second term, raised nearly $27 million through March 31, though donors may be trying to tee her up for a presidential bid in 2020.

Outside groups will likely pump tens of millions into the Texas race -- more from each side if it looks competitive.

"I think it has less to do with Cruz, maybe even less to do with me than you might imagine," O'Rourke said. "I think it has a lot to do with where the country is and where the people of Texas want the country to go." At his campaign events, he said, Texans are mainly concerned about health care, jobs and infrastructure.

"Rarely does someone stand up to say something ugly about the junior senator or the president," O'Rourke said.

As for the money, he said, it helps support an army of volunteers.

"The money helps to amplify that so that if you didn't come to that town hall in North Richland Hills or Flower Mound, and I was unable to knock on your door in DeSoto, there's an opportunity for me to advertise in newspapers or online or on TV or radio to engage with you," he said.