This story has been updated.

A “mystery” Senate Republican has blocked a traditionally noncontroversial bill that would provide more than 3.9 million veterans and their survivors with a cost-of-living adjustment for the benefits they receive, Sen. Patty Murray, D-Wash., chairwoman of the Senate Armed Services Committee, charged Thursday.

The Veterans' Compensation Cost-of-Living Adjustment Act passed the House on July 9 and would provide a 1.9 percent increase in disability benefits for veterans and their surviving spouses, matching the planned increase in Social Security benefits.

Murray decried the Senate development, saying in a statement, “this is stunning, particularly because we still don’t have any indication why someone would block a cost-of-living adjustment for veterans and their surviving spouses, many of whom are struggling to make ends meet.

“This adjustment for our disabled veterans is hard-earned and well-deserved,” she continued. “My hope is that whichever senator has decided to hold up this bill will at least come forward to own up to it. That way we can move forward to overcome their opposition and get our veterans the support they need.”

The increases were supposed to go into effect on Dec. 1.

The Congressional Budget Office said on Sept.19 that it expected the fiscal 2013 veterans COLA to be 1.3 percent and cost $686 million that year and $915 million in subsequent years. Veterans covered by disability and compensation programs under the Veterans Affairs Department received a 3.6 percent COLA in fiscal 2012.

Bob Wallace, executive director of the Veterans of Foreign Wars, reacted angrily to the Senate’s COLA hold. “It is outrageous that disabled American veterans are once again being held hostage to partisan politics,” he said in an email statement. “There is no justification for this hold, and to do so anonymously is beneath the dignity of any member of Congress.”

Dave Autry, spokesman for Disabled American Veterans said, “we hope the hold will be released as soon as possible so vets can get the cost of living increase they deserve.”

When the Hose passed the veterans COLA bill this summer, Rep. Jeff Miller, R-Fla., chairman of the House Veterans’ Affairs Committee said, “we have an obligation to the men and women who served this nation to make sure we are doing everything we can to keep the promise made to them. Today we upheld that promise.”

He noted, “veterans have enough to worry about without the added stress of not knowing if their cost-of-living adjustments will be held up in a political tug of war.”