NEW YORK — TransCanada Corp. expects the U.S. State Department to issue a supplemental environmental impact statement for the rerouting of its Keystone XL pipeline "quite quickly," a top company executive said.

"Whether that’s one week or two weeks, that’s hard to say. But they’ve certainly led us to the view that it’s imminent," TransCanada president of energy and pipelines Alexander Pourbaix said during the company’s fourth-quarter earnings call.

The company expects a presidential permit for the much-delayed project to come in the first half of the year.

"Once the (supplemental environmental impact statement) is issued, we are under the belief that the State Department is in possession of every piece of evidence they could require to make a decision," Pourbaix said.

While the permitting process for Keystone is progressing, the Calgary, Alberta-based company has run into some opposition to its Gulf Coast pipeline, which is about 45 percent complete.

"Many out-of-state or professional ... activists have done their best to slow down the project and stop our project, primarily in Texas," TransCanada president and chief executive officer Russ Girling said during the call. However, the company still expects the 485-mile, 36-inch line between Cushing, Okla., and Nederland, Texas, to be completed by year-end.

Further underlining a recent shift in investments to oil from natural gas, for which prices are low, the company is looking to repurpose parts of its Canadian Mainline natural gas pipeline to move oil to eastern Canada from western Canada, replacing rail transport.

"Rail is at least twice as expensive," Pourbaix said of the reasoning behind the proposed switch. "Every barrel you move by rail emits three times the greenhouse gases that a barrel moved by pipe does."