* Fifty three Senators sign letter, up from 18 in November
* Obama expected to decide fate of pipeline later this year
* Letter comes a day after Nebraska approves pipeline
By Timothy Gardner
WASHINGTON, Jan 23 (Reuters) - A bipartisan group of more than half the 100-member U.S. Senate has urged President Barack Obama to approve the northern leg of the Keystone XL pipeline project, which would connect Canadian oil sands to refineries in Texas.
"This is about something that Americans want. It's about energy for this country," Senator John Hoeven, a North Dakota Republican, told reporters on Wednesday.
Hoeven and Senator Max Baucus, a Montana Democrat, wrote a letter to Obama, signed by 51 other senators, urging him to approve the TransCanada Corp project, which has been pending for nearly four and a half years.
The letter came a day after Nebraska Gov. Dave Heineman approved a revised route for the pipeline to travel through the state while avoiding ecologically sensitive areas.
"Nebraska has now addressed the outstanding concerns you raised when you denied the permit, and we therefore urge to finish expeditiously the review process and approve the pipeline" the letter said.
Hoeven and Baucus represent the booming Bakken oil region. The $5.3 billion pipeline would carry 830,000 barrels of oil a day including some from the Bakken. The southern section of the project, from Texas to Oklahoma, is already being built since it did not require a federal permit as it does not cross the national border.
The two senators organized a similar bipartisan effort in November that drew signatures from 18 senators, nine Republicans and nine Democrats.
Nine Democrats also signed Wednesday's letter, but this time were joined by 44 Republicans who urged Obama not to delay.
"We ask you not to move the goal posts, as opponents of this project have pressed you to do," the senators' letter said.
The State Department's environmental review of the line is expected any day and there will be a public comment period after that, which could help determine exactly when the administration will decide on the project.
Interest in the fate of the pipeline has been heightened after Obama's vow at the start of his second term to fight climate change.
Hoeven told reporters that he would soon meet with Senator John Kerry, Obama's nominee to become secretary of state, and has been a steady advocate of taking action on climate change.
Environmentalists want the administration to reject the pipeline because the oil sands it would carry are more carbon intensive than average crude refined in the country.
Groups including 350.org and the Sierra Club plan a march on Washington on Feb. 17. In 2011 protests at the White House drew thousands and were credited with slowing the State Department's review.
Hoeven said that emissions from the oil sands are not a concern because producers are gradually moving to cleaner technologies to extract the fuel and because the oil will find its way to market no matter if the pipeline is built.
An initial State Department review also indicated the oil would get used whether or not Keystone is approved. Environmentalists are hoping the department will adjust that part of its review.
Hoeven added that if Obama does not move forward on the line by April he would reintroduce legislation enabling Congress to approve the pipeline.