The U.S. State Department last week issued a 2,000-page draft environmental impact statement on the pipeline. The report said there would be few net environmental effects from the project but noted it was also weighing factors like increased U.S. oil production and higher rail traffic for crude oil in its assessment.
Upton, chairman of the House Energy and Commerce Committee, said he was concerned the White House might not act in the project's favor.
"There is still no guarantee this pipeline will be approved absent an act of Congress," he said in a statement. "We fear the delays have allowed the opposition to grow so out-of-control that congressional action is still necessary to get the pipeline built."
Supporters like Upton say the project would provide economic stimulus while supporting North American energy independence. Detractors express concern about the level of greenhouse gas emissions associated with oil production and the broader environmental concerns.
Stephen Kretzmann, director of Keystone opponent Oil Change International, said he was questioned the State Department's assessment on the potential environmental impact. There "are huge holes that cause us to question the validity of State Department's analysis."