By Patricia Zengerle
WASHINGTON (Reuters) - The U.S. Senate voted on Tuesday to limit debate on a $612 billion defense authorization bill, clearing the way for a vote on passage, although the measure's future is clouded by a dispute between Republicans and Democrats over government spending policy.
The White House has said President Barack Obama would veto the bill if it is passed in Congress because of the "irresponsible" way it boosts military spending.
The annual National Defense Authorization Act measure sets spending policy for the Department of Defense but does not appropriate the funds. The Senate is expected to vote on final passage on Wednesday.
The Senate vote on the procedural motion was 73-26, well over the 60 needed for the bill to advance.
The House of Representatives passed the NDAA last week.
The NDAA uses some $90 billion in discretionary funds meant for war spending to allow the Pentagon to sidestep mandatory "sequestration" budget cuts.
Obama and his fellow Democrats want Republicans to work out a longer-term budget deal to ease the automatic spending constraints not just on military spending but also on many domestic programs.
Republicans say Democrats want to preserve irresponsible spending on pet programs and are holding national security hostage.
Republican Senator John McCain, the chairman of the Senate Armed Services Committee, said it would be "disgraceful" for Obama to veto the bill over a budgetary issue.
"This shows the disdain they have for the military and national security," McCain told reporters at the Capitol.
Democrats counter that the Department of Defense would be better served by a multi-year budget deal than relying on a one-year budget "gimmick."
(Additional reporting by David Lawder; Editing by Doina Chiacu)