Senate Democrats said Tuesday they'll push amendments to legislation approving the Keystone XL pipeline requiring that it's built with domestically produced steel and that the oil it carries is used in the U.S.

"The project now would simply pump American oil across the American heartland — not to be used here — but to be shipped overseas," Sen. Charles Schumer of New York, the Senate's third-ranking Democrat, said at a news conference.

With polls showing a majority of voters supporting Keystone, Democrats have sought to undermine its purported benefits to the U.S. They argue that the oil from Alberta is destined for overseas markets — an assertion disputed by pipeline builder, TransCanada Corp.