Hoeven said in the weekly GOP media address the pipeline would create numerous jobs, strengthen the economy and reduce dependence on oil from the Mideast.
"It's hard to imagine a project that is more in the national interest and the interest of the American people," Hoeven said.
House and Senate Republican lawmakers have pressed the White House to approve Keystone, which would transport oil recovered from oil sands mined in Canada to refineries on the U.S. Gulf Coast.
Under the payroll tax deal, the White House has until Feb. 21 to decide whether to approve the project.
Canadian pipeline company TransCanada wants to build Keystone XL to supplement its existing pipeline carrying tar sands oil from Alberta. Keystone XL would send roughly 15 million barrels of oil to the United States every month.
Critics cite the number of spills on the existing Keystone oil pipeline and the potential environmental impact of heavy crude oil from tar sands projects in Alberta.
Hoeven noted warnings gas prices could rise to $4 a gallon this year and said the pipeline would reduce U.S. reliance on foreign oil.
"Yet the president is saying 'no' to the Keystone XL pipeline, he's saying 'no' to a project that will bring more than 700,000 barrels of oil a day from our friend and ally, Canada, and he's virtually assuring continued reliance on the Middle East," Hoeven said. "That makes no sense, and it's a matter of great concern for our national security, particularly with what's going on in Iran."