President Obama announced that his administration is rejecting the controversial proposal for the Keystone XL oil sands pipeline, which would have transported 700,000 barrels of oil daily from Canada, Montana and the Dakotas to U.S. refineries in Houston.

The proposal has been under review for more than three years.

Because the pipeline would have crossed an international border, its proposal required a Presidential Permit from the Department of State.

Obama acted before a Feb. 21 deadline Congress set after he postponed a decision in November while a revised Nebraska route was being reviewed. According to The Hill, Obama's rejection "will escalate an explosive election-year fight with Republicans and major business groups."

The American Trucking Associations previously expressed its support of the pipeline. The organization said the pipeline would enhance U.S. energy security, create jobs and reduce air emissions associated with transporting this oil to market.

ATA urged the State Department to issue the permit for the pipeline. "The State Department can help ensure that the 18-wheelers that deliver America's essential goods like food, fuel, and medicine have reliable access to that fuel by approving the Keystone XL project," said Bill Graves, ATA president and chief executive officer, in an October testimony for the pipeline.

While ATA had not issued any type of formal statement as of this writing, the association's chief economist, Bob Costello, had this to say on Twitter: "Disappointing that XL Pipeline Application was completely rejected. They should start the project while working out Nebraska rerouting."

Observers note there still may be hope for the pipeline. In a written statement, the State Department said: "The Department's denial of the permit application does not preclude any subsequent permit application or applications for similar projects."