Colorado Republican Rep. Cory GardnerCory Scott GardnerThe siren of Baton Rouge Senate confirms John Demers to head DOJ national security division Senate rejects bipartisan measure as immigration votes begin MORE raised $4.35 million in the third fundraising quarter of the year, his campaign announced Tuesday.

At the end of August, Gardner had $3.3 million cash on hand for the final stretch of his battle with Sen. Mark UdallMark Emery UdallDemocratic primary could upend bid for Colorado seat Picking 2018 candidates pits McConnell vs. GOP groups Gorsuch's critics, running out of arguments, falsely scream 'sexist' MORE (D). The campaign has also added $750,000 to its October ad buy.

The third quarter haul is nearly $2 million more than Gardner raised during the second quarter, and he said in a statement that the "momentum is building" for his challenge to Udall.

"The momentum on the ground is building as Coloradans realize the road to the majority runs directly through our state," he said. "It's time for a new generation of leadership in the Senate that is accountable to the next generation."

Most public polling has shown the two tied for the seat. Udall hasn't yet released his third quarter fundraising numbers.