By Laura Barron-Lopez - 05/14/14 08:40 AM EDT
The American Energy Alliance is spending more than $400,000 on a new ad accusing Sen. Mark UdallMark UdallEnergy issues roil race for Senate Unable to ban Internet gambling, lawmakers try for moratorium Two vulnerable senators lack challengers for 2016 MORE (D-Colo.) of opposing construction of the Keystone XL pipeline.
The conservative grassroots group claims Udall, who is up for reelection this year, wants to kills the $5.4 billion project. The ad is set to run through May 23.
"Sen. Mark Udall is siding with Washington lobbyists and special interests to kill it," the ad states.
The energy alliance says Udall opposes the pipeline because he voted against an amendment in 2012 that would have approved construction, and two other amendments in 2013 that would have promoted investment in refining sectors through the pipeline.
Udall has yet to take a formal stance for or against the pipeline.
Udall spokesman Mike Saccone said the reason the senator didn't vote for the Republican and Democratic budget amendments on Keystone last year was because he felt it wasn't Congress' place to do so.
"Sen. Udall still believes Congress should not be injecting politics into the review process," Saccone said.
Rep. Cory GardnerCory GardnerInvestments in research and development are investments in American jobs EPA won’t pay Colorado county for some mine spill costs The Trail 2016: Trump applies presidential polish, Cruz adds VP MORE (R-Colo), who is running against Udall, backs Keystone's construction and has worked to turn the pipeline into an issue in the race.