Mary Kuhlman -- Missouri News Service

Despite approval from both of Missouri's U.S. senators and other lawmakers, President Barack Obama on Tuesday vetoed legislation that would have approved construction of the Keystone XL Pipeline.

It isn't the last word on the massive pipeline project, which would transport oil from tar sands in Canada to Texas and cross through many states, including Missouri. But Julian Boggs, outreach director for global warming at Environment America, described the veto as a "great win" for those who have fought for years against the project.

"We're on the heels of the hottest year on record, and it's clear that we have to put the brakes on global-warming pollution," he said. "This dangerous and dirty project would, unfortunately, put our foot on the accelerator. So, we chalked up an important victory, and the pen was mightier than the pipeline."

Supporters of the pipeline say it would create jobs, but Boggs noted that in many states, jobs in clean-energy sectors are growing at a fast clip.

There are rumblings of a Senate attempt to override the veto, as early as next week. The White House said the president will wait for completion of environmental and regulatory reviews before he approves or rejects the pipeline project.

Keystone XL proponents also say it would help reduce the country's dependence on foreign oil. But Boggs counters that the environmental risks are too great.

"The proposed pipeline would cross over the Ogallala aquifer, which is really our heartland's source for clean water and it's a risk we can't afford to take," he said. "The extraction of so much fossil fuels and extra carbon into our atmosphere is a risk that our climate can't afford to take."

Last month, an oil pipeline accident leaked nearly 50,000 gallons of crude into the Yellowstone River. The Keystone XL is proposed to carry up to 830,000 barrels of oil a day.