WASHINGTON — The company seeking to build the Keystone XL oil pipeline asked the Obama administration on Monday to suspend its yearslong review of the project, potentially bringing an abrupt halt to a politically charged debate that had become part of a broader struggle over President Obama’s environmental policies.

It was not immediately clear whether the administration would grant the request, which was swiftly denounced by environmental activists as a bid to dodge a near-certain rejection of the pipeline. Allowing the delay would push off a decision until after the 2016 presidential election.

The company’s request introduced a new element of uncertainty into the administration’s decision-making process, offering the potential to free Mr. Obama from a politically difficult choice that has hung over much of his presidency. But if anything, it appeared to intensify pressure on him from crucial Democratic constituencies to reject the pipeline or risk being blamed for punting to another president. A delay would keep the issue alive in the presidential campaign.

TransCanada, the Alberta company seeking to build the 1,179-mile pipeline, made its request in a letter to the State Department, which must approve cross-border projects and had been reviewing its application for a presidential permit.