U.S. Republicans have failed to get their amendment aimed at securing approval for the proposed Keystone XL pipeline through the Democrat-dominated Senate.

The amendment would have bypassed the White House's objections to the $7.6-billion US project, which would carry mostly Alberta oilsands crude to refineries along the Texas coast.

It needed 60 votes to pass, but received only 56 in favour.

Passage would have been an embarrassment for the administration, but despite public pressure on several Democrats in an election year to do something about rising gasoline prices, the motion failed to draw enough support.

Before the vote, Republican House Speaker John Boehner accused President Barack Obama of getting his priorities wrong.

"By personally lobbying against the Keystone pipeline, it means the president of the United States is lobbying for sending North American energy to China and lobbying against American jobs," Boehner said at a news conference.

The pressure on Democrats grew last week when former president Bill Clinton came out in favour of Keystone XL.

In January, the U.S. government denied a permit for the project, but left the door open for TransCanada to apply for a new one.

Obama said a deadline imposed on his administration by the Republicans to make a decision by Feb. 21 didn't allow enough time to adequately study a new route through Nebraska, so he had no choice but to reject the project.

On Tuesday, TransCanada said a plan for a new route around Nebraska's environmentally sensitive Sandhills region would be ready within weeks and that the firm would resubmit its permit request to the U.S. State Department.