U.S. President Barack Obama said on Friday that construction of the Keystone XL pipeline to transport crude oil from Canada to the U.S. Gulf Coast would only nominally benefit American consumers and workers. "There is very little impact - nominal impact - on U.S. gas prices, what the average American consumer cares about," Obama told reporters during an end-of-year press conference. In his strongest comments on the Canada-to-U.S. pipeline to date, Obama picked apart some of the most common arguments proponents have used to urge the president to approve it: that it would create jobs, lower domestic gasoline prices and...