WASHINGTON -- The Senate appears poised to hand the White House another victory with a measure that would make permanent an expansion of government spy powers and shield phone companies from liability for assisting government eavesdropping.

With floor consideration scheduled to start today, Democrats are split on how to cut back on the administration's surveillance powers. The only option that appears to have sufficient backing is a bipartisan measure the White House has blessed. Opponents of the White House-backed bill are...