WASHINGTON — Senate supporters of the long-delayed Keystone XL pipeline conceded Thursday they lack the 60 votes necessary to pass legislation authorizing immediate construction of the project, but said they remain hopeful of prevailing.

“At this point we’re still working to get 60,” said Sen. John Hoeven. R-N.D., as he and Sen. Mary Landrieu, D-La., introduced a bipartisan bill to end the delays and build the proposed oil pipeline from Canada to the United States.

Landrieu, who chairs the Senate Energy Committee, faces a tough re-election challenge this fall, and has said she will use all her power to make sure the project is built.

In remarks on the Senate floor, she said supporters of the project think “there is so much potential for Canada, the U.S. and Mexico ... to become completely not only energy independent, but an energy powerhouse for the world.”

She added, “what signal does it send if America is not willing to do its part when it comes to production right here?”

Landrieu and Hoeven said the legislation has the support of 11 Democrats and all 45 of the Senate’s Republicans, a total of 56 of the 60 that will be needed. “A vote on the bill is expected in the coming days,” they added.