WASHINGTON — With the recent dip in oil prices, the Environmental Protection Agency wants the State Department to “revisit” how much of a toll the Keystone XL oil pipeline would have on global warming.

The EPA suggests that lower oil prices could make the pipeline more important in the development of the oil sands, and thus a chief culprit in the “significant greenhouse gas emissions” they would produce. A January 2014 environmental analysis by the State Department found that the oil sands — which it said would significantly increase greenhouse gas emissions over conventional crude oil — would be developed regardless of whether the pipeline was built. But that conclusion was based on higher oil prices. Oil, the EPA points out, was trading at $50 per barrel last week.

“Given the recent variability in oil prices, it is important to revisit these conclusions,” wrote Cynthia Giles, assistant administrator of EPA’s enforcement office.

The comments sent Monday to the State Department come as the House prepares to vote next week and send to President Barack Obama’s desk a bill approving the Keystone XL oil pipeline. The Senate voted 62-36 last week to build the $8 billion project that would connect with existing pipelines to carry more than 800,000 barrels of crude oil a day to refineries along the Texas Gulf coast. That vote was short of the two-thirds majority needed to override the veto the White House has promised.

Obama has said all along that he would wait for the review process to conclude, and that the pipeline could not exacerbate global warming.

The EPA’s comments leave open the possibility that the State Department could do additional analysis, delaying the project’s review again.

The American Petroleum Institute said the EPA was “inventing new excuses” to delay the project, which was first proposed in 2008, when oil prices were lower than they are now.

“Suggesting that the drop in oil prices requires a re-evaluation of the environmental impact of the project is just another attempt to prolong the KXL review,” said Finkel. “Keystone XL was put forward when oil was less than $40 a barrel so price has little impact on the project.”

But environmentalists, who have fought vigorously to kill the pipeline, applauded the EPA’s assessment Tuesday.

“The EPA’s assessment is spot-on. There should be no more doubt that President Obama must reject the proposed pipeline once and for all,” said Danielle Droitsch, a director for the Natural Resources Defense Council who specializes in Canada’s tar sands.

A State Department spokeswoman said it would take into account the views of all agencies in the review process.