WASHINGTON — Rep. Beto O'Rourke's torrid fundraising is already the stuff of legend for Texas Democrats eager to oust Sen. Ted Cruz and break the GOP's long grip on the state.

When the next round of campaign finance reports hits later this month, he's sure to raise even more eyebrows.

O'Rourke pulled in more than $11 million in July and August alone, just through ActBlue, the Democratic fund-raising platform. Last week, the three-term El Paso congressman also set — and exceeded — an aggressive one-week, $5 million online goal.

That's $16 million that hasn't yet shown up on his campaign finance reports. It doesn't count whatever he pulled in through ActBlue in September, nor all the other donations that came his way since July 1.

That puts O'Rourke's tally at nearly $40 million — an astonishing sum not just for a challenger but for any Senate candidate anywhere, ever.

Donations flowing through ActBlue alone account for $25.4 million of that — another eye-popping sum that shows the power of harvesting donations from hundreds of thousands of low-dollar supporters, rather than having to rely on the relative few who are willing to cut a check for $2,700, the current legal cap.

"I don't know the last Democrat who's raised that much money," said Jennifer Duffy, managing editor at the Cook Political Report and a top Senate campaign handicapper.

She recently shifted the race to "toss-up," a development that sent shudders through the GOP ranks, given that Texas hasn't elected a Democrat statewide since 1994. But most polls show a tight race, and Cruz lags in fundraising.

"It says a lot about O'Rourke," Duffy said. "People like his message: people, no PACs. There's an optimism to his campaign that voters don't get to see a lot. And there's definitely an anti-Cruz sentiment among these donors."

From March 31, 2017 — the day he announced his bid for Senate — through the end of July 2018, O'Rourke brought in $17.3 million from 518,560 donations processed by ActBlue.

He brought in another $2.9 million in July, according to FEC filings from ActBlue. In August, according to figures crunched by ProPublica, he brought in $8.1 million.

September figures aren't yet available. The O'Rourke and Cruz campaigns haven't yet filed reports due Oct. 15 that cover their own fundraising from July to September.

Even without those tallies, the Texas Senate race is the most expensive in the country for 2018.

As of midyear, the rivals had raised a combined $47 million.

O'Rourke drew national headlines when he topped $10 million for the second quarter of 2018 and caught up to the incumbent's six-year haul in just 18 months. The race is likely to top $100 million in combined spending by candidates and outside groups — super PACs, party committees and other entities that have already begun pouring money into Texas, not all of which have to disclose their funding sources.

The first Senate races to break the $100 million mark were in North Carolina and Colorado, in 2014.

Two years later, four Senate races broke nine figures thanks to massive spending by outside groups. In Pennsylvania, Sen. Pat Toomey won a second term in a contest that holds the current record at $188 million, followed by New Hampshire ($141 million), Nevada ($128 million) and Florida ($110 million).

By comparison, the last truly competitive Senate race in Texas drew just $23.6 million.

That was in 2002, when Republican John Cornyn — now the Senate majority whip — defeated Democrat Ron Kirk, a former Dallas mayor and future U.S. trade ambassador.

When Cruz won his seat in 2012, the tally hit nearly $70 million, but Democrats accounted for hardly any of that. More than $28 million came then-Lt. Gov. David Dewhurst, who outspent Cruz 2-to-1 and still lost the GOP nomination — proving that money isn't everything in politics.

"Money is relative. It's safe to say there's never enough in Texas," nor in Florida or California, said Duffy. "It's enough to be competitive. ... He can go point for point with Cruz on television. He's winning the yard sign war."

And, most importantly, O'Rourke is building a massive grassroots organization.

The senator may lag in fundraising but he has other advantages. He's universally known in Texas. He has friends at the White House to pitch in: Vice President Mike Pence will campaign with him Monday in Dallas, and President Donald Trump plans to headline a rally later this month for Cruz, somewhere in Texas.

Cruz has an impressive fundraising list compiled during his first Senate run, his anti-Obamacare crusade and his failed presidential effort. But Republicans have nothing equivalent to ActBlue, Duffy noted, making it harder for them to raise massive sums online from fans around the country, as O'Rourke has done.

"This is more than just an anti-Trump and anti-Cruz message. People like the different kind of campaign that O'Rourke is running. His use of social media, the commitment to visit every county, which is not easy," she said. And the quirkier moments of the campaign, like "seeing a member of Congress skateboard around."