Rep. Mark Udall (D) raised more than $1.1 million in the third quarter for his Senate campaign, finishing September with more than $3.1 million in cash on hand.

Udall is set to face former Rep. Bob Schaffer (R) in the general election. Schaffer’s third-quarter numbers were unavailable at press time.

“Considering the historic difficulties of fundraising in the 3rd quarter of an off-year, this is a monumental achievement that reflects the growing momentum and strength of Mark’s campaign for the United States Senate,” Udall campaign manager Mike Melanson said in a statement.

The race between Udall and Schaffer to replace retiring Sen. Wayne Allard (R) is expected to be a closely fought affair. An independent poll released Friday showed Udall with 36 percent of the vote and Schaffer with 35 percent. The poll of 504 registered voters, conducted Sept. 11-15 by Ciruli Associates, had a 4.4-point error margin.

— David M. Drucker