President Barack Obama announced Friday that he is rejecting the Keystone XL pipeline proposal, saying the project "would not serve the interests of the United States."

The president cited concerns about the impact on the environment and a political climate that over-hyped the pipeline's benefit.

"While our politics have been consumed with whether this pipeline would increase jobs and lower gas prices, we have increased jobs and lowered gas prices," Obama said.

The 1,179-mile pipeline would transport oil from heavy tar sands in Alberta, Canada, to the Gulf Coast. A 875-mile northern portion had been projected to cost an estimated $8 billion to build and has faced serious contention from the likes of environmentalists, Democrats and landowners in its path.

Related: Keystone X'd? TransCanada Asks U.S. to Suspend Pipeline Application Review

In February, President Obama vetoed a bill to approve the Keystone XL pipeline, saying that the proposal attempted “to circumvent longstanding and proven processes for determining whether or not building and operating a cross-border pipeline serves the national interest.”

Obama previously said the bill conflicted with executive processes as he was waiting for a second report from the State Department to assess the pipeline’s suggested economic and environmental impact. Obama has said that the choice to build the Keystone XL Pipeline falls to the executive branch due to its traversal of international borders.

In March, the Senate attempted to override Obama’s veto but fell just short of the necessary 67 votes. At the time, former Speaker of the House John Boehner called the failure of the bill a “national embarrassment.”

The Keystone pipeline has been a sensitive topic for the Obama administration. Speaking at the Glacier Conference in August, Obama emphasized the urgency of climate change.

"We are not moving fast enough. None of the nations represented here are moving fast enough." But environmentalists have critiqued the president as being hypocritical in this view,” Obama said.

Related: What Happens if the Keystone XL Pipeline Isn't Built?

The White House has increasingly honed in on climate change as a core policy priority and the president is also eying a major international climate change agreement he hopes will come from a summit in Paris in December.

That agreement could help secure his legacy as the first sitting president to address global climate change in a substantive way, environmental policy experts said.

Related: Breaking the Ice: Obama Seeks to Cement Climate Change Legacy

But ultimately, Obama’s decision on the pipeline won’t affect the export of oil from Canada. The pipeline would simply increase the distance of the already existing Keystone Pipeline, increasing the amount of barrels per day to 830,000.

A 2014 report from the State Department determined that the pipeline would contribute to climate change, but no more so than any other alternative options for transporting the oil. The State Department report found that the contribution to climate change would be better with the pipeline than with the rail or tanker options.

The report also found, however, that significant economic growth would result, including 42,100 jobs and $3.4 billion or approximately 0.2 percent of the U.S. GDP.

Related: 2016 Field Reacts to Keystone Announcement

GOP presidential candidates were swift in their rebuke of the president's decision on the Keystone XL pipeline on Friday, while Democratic 2016 candidates expressed support for the administration's call.

"Although presidential hopefuls will no doubt seize on this decision, the fact remains that the Keystone pipeline would have represented a relatively insignificant addition to U.S. energy infrastructure," said Bruce Huber, an associate professor of law at the University of Notre Dame who specializes in environmental, natural resources and energy. "The pipeline had acquired an outsized symbolic importance to both supporters and detractors, even as other pipeline activity proceeded."