By Keith Laing - 05/22/12 09:24 PM EDT
"By allowing tar sands access to the lucrative international market, Keystone XL would finance further expansion of tar sands extraction, worsening climate change and undermining efforts to move to clean energy," the group said in the study, which was titled "Keystone XL: A tar sands pipeline to higher oil prices."
"Pipeline supporters cite high gasoline prices as a reason to build the project," the NRDC study continued. "The truth is that Keystone XL is likely to both decrease the amount of gasoline produced in U.S. refineries for U.S. markets and increase the cost of producing it, leading to even higher prices at the pump."
The controversial cross-country pipeline, which was rejected earlier this year by President Obama, is one of the biggest areas of disagreement between the Republican-led House and the Senate, which is controlled by Democrats, on the proposed highway bill.
The House included a mandate forcing President Obama to approve the pipeline the extensions of transportation funding it passed, and the lower chamber voted to reaffirm its position last Friday
The Senate meanwhile did not include the mandate in a two-year, $109 billion transportation it passed earlier this year, and supporters of the Senate's highway measure point out that a vote on Keystone in the upper chamber failed earlier this year.