Republican Gov. Jack Dalrymple, U.S. Sen. John Hoeven and U.S. Rep. Kevin Cramer sent a letter Wednesday to Obama imploring him to authorize the Army Corps of Engineers to approve the pipeline's crossing under the Missouri River in North Dakota.
Democratic U.S. Rep. Heidi Heitkamp says she also pressed the White House this week to intervene.
The crossing is the final large segment of the $3.8 billion pipeline, which will carry North Dakota oil to Illinois. The work is delayed while the Corps consults with the Standing Rock Sioux, who oppose the project.
Obama raised the possibility of rerouting the pipeline earlier this month.
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