A bipartisan group of four senators is pressuring President Obama to approve the Keystone XL pipeline, including Louisiana Democrat Mary Landrieu, who faces a potentially tough re-election battle in 2014.

In a joint statement released Thursday, Landrieu, Senate Finance Chairman Max Baucus, D-Mont., and Republican Sens. John Hoeven, of North Dakota, and John Thune, of South Dakota, said it was time for the Obama administration to approve construction of the pipeline, which would carry oil from Canada to the refineries along the Gulf Coast. The White House has put off a decision on the pipeline, saying it’s evaluating environmental concerns.