The United States said Tuesday it would carry on with its review of the controversial cross-border Keystone XL oil pipeline project despite a request from builder TransCanada for a pause in the process.

The company said Monday it had asked Secretary of State John Kerry to suspend the review, citing litigation pending in Nebraska, one of the states through which the pipeline would run to bring crude from Canada's Alberta province to the Gulf of Mexico.

TransCanada said a ruling in Nebraska would take seven to 12 months. A halt in the review might thus delay a decision on building the pipeline until after the US presidential election in November 2016.

The State Department said it has received TransCanada's letter. "We will issue a response, but we're going to continue our review process," said a State Department spokeswoman, Elizabeth Trudeau.

She stressed that TransCanada had requested a pause in the review process and had not withdrawn its request for permission to build the pipeline.

The request for a suspension came just before Justin Trudeau of the Liberal party takes power as prime minister of Canada on Wednesday.

While not opposed outright to Keystone XL, he has expressed more reservations about the potential environmental impact of the project than his predecessor, Stephen Harper.

Harper had been urging the United States to approve the 1,179-mile (1,900-kilometer) pipeline. Kerry recently said Trudeau's election victory would not influence the eventual US decision on the pipeline.

The State Department spokeswoman said Kerry wanted the review completed as swiftly as possible.

The administration of President Barack Obama and the US environmental lobby have concerns about the potential impact of such a project, which would carry dense oil from the tar sands of central-western Canada, diluted with benzene.

For conservatives and some Democrats in the regions through which the pipeline would pass, the pipeline means jobs and energy independence.

Many other Democrats are calling on Obama to deny TransCanada permission to build the pipeline out of concern over climate change and protecting the environment.

Kerry's predecessor at the State Department, Hillary Clinton, has come out against Keystone as part of her campaign for the White House, reinforcing Canadian fears that the project will be blocked.

But the Obama administration has yet to make a decision, and parts of the energy sector on both sides of the border are lobbying Washington to approve it.

nr-burs/dw/sst