WASHINGTON — Democrat and Republican senators are urging U.S. President Barack Obama to approve the Keystone XL pipeline, now that Nebraska has given the controversial project its blessing.

On Wednesday, 53 senators signed a letter to Obama calling on him to approve the pipeline, and also put in place a timeline by which he'll give it the OK.

Senators also wrote the president in November, asking him to approve the project.

While Republicans have long supported the $7-billion pipeline for the jobs and energy security it would create, Democrats are now joining the chorus.

Joe Manchin, a Democrat senator from West Virginia, said Wednesday building the pipeline would strengthen America's relationship with Canada, which he called the country's "best partner.”

"Canada is the largest trading partner of 35 different states. It's unbelievable. Back home in West Virginia, we have this thing where we'd rather work with our friends than our enemies," he said.

"We've never worried about Canada attacking us, or turning against us, or causing problems. They've always been there as the best partner we've ever had."

A day earlier, Nebraska Gov. Dave Heineman also wrote the president informing him he was approving TransCanada's new route around the environmentally sensitive Sandhills region in his state.

Nebraska's approval was a final hurdle the project had to clear.

"We've addressed the safety concerns, and there are no safety concerns," said Montana Democrat Sen. Max Baucus. "America can't afford to wait any longer for these jobs. We've waited more than four years. The time has come now."

A year ago, Obama rejected TransCanada's application — but encouraged the company to reapply — to build the pipeline that would ship about 700,000 barrels of crude a day from Alberta's oilsands to refineries along the Gulf of Mexico.

At the time, Obama said Republicans had imposed a deadline that did not allow enough time to study the environmental impacts in Nebraska of the new proposed route, which has now been approved.

On Tuesday, officials from the U.S. State Department said a decision on Keystone would not be forthcoming before the end of March at least.