After many months and several polls that showed Rep. Mark Udall (D) with a sizeable lead over former Rep. Bob Schaffer (R) in the open Senate race, a GOP- sponsored survey taken last week had the two candidates in a statistical tie.

The Tarrance Group, in a poll commissioned by the National Republican Senatorial Committee, found Udall ahead of Schaffer by just 1 point, 40 percent to 39 percent. The survey of 495 likely voters was taken Sept. 2-3 and had an error margin of 4.5 points.

“Schaffer actually has a slight advantage in terms of intensity, as his ‘definite’ vote is 3 points higher than Udall’s definite vote,” according to the polling memo prepared for the NRSC.

Matthew Miller, a spokesman for the Democratic Senatorial Campaign Committee, dismissed the poll as having no credibility. Miller noted two independent polls taken in August, one by Mason-Dixon Polling & Research and the Denver Post and another by Suffolk University, showed Udall with a healthy lead over Schaffer.

“With two independent public polls showing Udall ahead by 10 and 8 points, this poll should be taken with the same credence as Bob Schaffer’s assertion that [convicted lobbyist] Jack Abramoff didn’t arrange his parasailing trip to the Mariana Islands,” Miller said.

The Tarrance Group’s survey also revealed:

• In the race to replace retiring Sen. Wayne Allard (R-Colo.), the generic ballot test showed voters favored a Democratic candidate 44 percent to 42 percent.

• In the race for Colorado’s nine electoral college votes, Sen. John McCain (R-Ariz.) led Sen. Barack Obama (D-Ill.), 47 percent to 45 percent.