Mitt Romney is vowing to approve TransCanada's Keystone XL pipeline on his first day on the job if elected U.S. president in November.
In a campaign ad unveiled on Friday, the presumptive Republican nominee asks voters to imagine Day 1 of his presidency, and lists Keystone as a top priority.
"Day One, President Romney immediately approves the Keystone pipeline, creating thousands of jobs that Obama blocked," the ad's narrator says.
Mr. Romney has been maligning U.S. President Barack Obama for months for failing to give the green light to Keystone. The president rejected the $7-billion pipeline earlier this year, but invited TransCanada to apply for another permit once the Calgary-based company rerouted the project around a crucial aquifer in Nebraska.
"I will build that pipeline if I have to myself," Mr. Romney said last month.
TransCanada recently came up with a new route for Keystone XL, one that skirts the Nebraska aquifer before joining up with the original proposed path of the pipeline.
Environmentalists say the new route continues to pose threats to Nebraska's drinking water since it still traverses the aquifer, only avoiding a portion of the state's Sandhills region where groundwater is close to the surface.
U.S. environmentalists have mounted a massive campaign against the pipeline, calling it a disaster waiting to happen and insisting it would sustain America's addiction to "dirty oil."
Keystone XL would transport oilsands crude from northern Alberta through six U.S. states to Gulf Coast refineries.
The debate over the pipeline became a political migraine for Mr. Obama. Keystone XL proponents said he was turning his back on much-needed American jobs by stalling on the Canadian pipeline, while environmentalists urged him to stand up to the oil industry as he promised to do while running for president in 2008.
The State Department will make the final decision on the pipeline because it crosses an international border.