Not counting the $22 million take of Florida governor Rick Scott earlier this year ($14 million of which came from his own personal funds), the previous record-holder was Republican Rick Lazio, who in 2000 raised almost $22 million in a single quarter when running for a NY senate seat against Hillary Clinton.
O'Rourke's campaign shared limited information from the third-quarter fundraising report, which will be filed with the Federal Election Commission and made public on Monday.
Drawing $38.1 million from over 800,000 donors, O'Rourke raised more than three times what Cruz did, despite the incumbent's lead in the polls.
The Houston Chronicle reported that the last three months have put O'Rourke's total funds at $60 million raised, which is the most out of any Democratic Senate candidate this year.
Rep. Beto O'Rourke, the upstart Democratic challenger to Texas GOP Sen. It's the most ever raised in a quarter by a US Senate campaign. Another pointed out that former President Barack Obama had raised $23.5 in the final quarter before the 2008 primary season kicked off.More news: Elizabeth Warren releases DNA test with 'strong evidence' of Native American ancestor
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The total was "powered by 802,836 individual contributions and without a dime from PACs, corporations or special interests", the campaign said in a press release.
Wilson says the race, which has drawn dominated attention statewide and nationwide due to the chance a Democrat could win a Senate seat in Texas again, might be pulling in money because it will be such a challenge.
These fundraising numbers come on the tail of a new Quinnipiac University poll showing that Cruz holds a 9 percentage point lead over O'Rourke.
O'Rourke has refused to go negative, instead recently recording a 30-second TV spot in real-time on Facebook live, declaring: "You've probably seen the negative attack ads seeking to scare you about what we're trying to do for this country at this critical moment" and offering a message of unity instead.
In a video to supporters Friday, O'Rourke touted his fundraising as a sign of the strong support he has from Texas voters, who have not elected a Democrat to the Senate since Lloyd Bentsen in 1988. Bill Nelson and Republican Gov. Rick Scott; more than $50 million had been raised through the second quarter.