O’Rourke, who in recent polls trailed Cruz in the heavily conservative state, thanked his more than 800,000 donors in the third quarter.
“It’s going to give us the resources we need to finish this campaign as strong as we possibly can,” O’Rourke told supporters in a video on Twitter. “We’re doing something absolutely historic, not only ensuring that we have the resources to run and to win but to make sure that our democracy once again is powered by people and only people.”
O’Rourke made the disclosure ahead of Monday’s deadline for candidates to report their fundraising to the Federal Election Commission.
The two campaigns were closely matched as of June 30, the most recent data available from the FEC, with each having raised more than $23 million. More recent figures for Cruz were not immediately available.
The progressive O’Rourke hopes to become the first Democrat to represent Texas in the U.S. Senate in 30 years.
The race will help determine the balance of power in the upper chamber of Congress, where Democrats are trying to pick up two more seats that would give them a majority, and be a check on President Donald Trump’s agenda.
Reporting by Scott Malone in Boston; Editing by Jeffrey Benkoe