WASHINGTON — The Obama administration, under sharp pressure from officials in Nebraska and restive environmental activists, announced Thursday that it would review the route of the disputed Keystone XL oil pipeline, effectively delaying any decision about its fate until after the 2012 election.

The State Department said in a statement that it was ordering a review of alternate routes to avoid the environmentally sensitive Sand Hills region of Nebraska, which would have been put at risk by a rupture of the 1,700-mile pipeline carrying a heavy form of crude extracted from oil sands formations in Alberta to refineries in Oklahoma and the Gulf Coast.

The move is the latest in a series of administration decisions pushing back thorny environmental matters beyond next November’s presidential election to try to avoid the heat from opposing interests — business lobbies or environmental and health advocates — and to find a political middle ground. President Obama delayed a review of the nation’s smog standard until 2013, pushed back offshore oil lease sales in the Arctic until at least 2015 and blocked new regulations for coal ash from power plants.

The proposed project by a Canadian pipeline company, TransCanada, similarly put the president in a political vise, squeezed between the demand for a secure source of oil and the thousands of jobs the project will bring, and the loud agitation of environmental advocates who threatened to withhold electoral support next year if he approved it.