WASHINGTON (Reuters) - The Republican-led U.S. Senate voted on Tuesday to begin debate on sweeping tax legislation, setting the stage for lawmakers to hold their final vote on the tax cut package later in the evening. The Senate voted 51-48 to debate the legislation about an hour after the House of Representatives approved what is widely expected to become the first overhaul of the U.S. tax code in more than 30 years. The debate period is due to last 10 hours officially but could be shortened to as little as five hours by parliamentary procedure. 