Barack Obama, the US president, is to make a final decision on the construction of a $7bn extension to Canada's Keystone pipeline to refineries in Texas.<br /><br />Environmental groups that helped elect the president say that the project is a threat to US farmland and to the Midwest region's largest aquifer - which nearly two million people depend on for drinking water.<br /><br />Meanwhile, labour unions, who also supported the president, are rallying behind the project due to its promise of thousands of badly needed construction jobs. <br /><br />Other people who support the extension say that the US needs the pipeline to secure energy dependence. <br /><br />Al Jazeera's Tom Ackerman reports from Washington.
