The White House said on Tuesday it would be "unusual" to pause the U.S. government's years-long review process of TransCanada Corp's proposed Keystone XL oil pipeline.
TransCanada has asked the U.S. government to suspend review of the $8 billion project that sparked a political war between environmentalists and the oil industry.
White House spokesman Josh Earnest said the State Department was still considering the Canadian company's request "to determine exactly what the request is, and what is motivating that request."
"But given how long it's taken ... it seems unusual to me to suggest that somehow it should be paused yet again," Earnest said at a news briefing.
The 1,200-mile (2,000-km) pipeline would help link Canada's heavy oil fields to U.S. refineries.
If granted by the U.S. State Department, the delay would likely take the decision from Democratic President Barack Obama and put it into the hands of the winner of the November 2016 presidential election.
"There's reason to believe there may be politics at play here," Earnest said.
He said Obama has tried to ensure that the eventual decision is based on the merits of the project, as determined by experts.
(Reporting by Doina Chiacu; Editing by Mohammad Zargham)