Udall the victim of a false ad; he did not vote for a carbon tax; Crossroads GPS is playing dirty tricks

An ad running in Colorado attacks Sen. Mark Udall for voting for a carbon tax that would raise fuel costs for middle class Americans. Factcheck.org says "he did no such thing".  The dirty tricks season is upon us.
http://www.factcheck.org/2014/07/more-carbon-tax-distortions/