Senate Democrats are trying to suss out the identity of a mystery Republican who blocked a cost-of-living adjustment veterans bill just before the upper chamber recessed.

“This is stunning,” said Sen. Patty Murray (D-Wash.), chairwoman of the Senate Veterans Affairs Committee. “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.”

The bill was cleared by all Senate Democrats but was blocked by at least one Senate Republican who has not come forward to claim responsibility.

Senate GOPs killed a veterans jobs bill before recess, though, with some contending that the usually bipartisan veterans issue was being used as a campaign-friendly victory lap by Democrats. Sen. Jeff Sessions (R-Ala.) raised a point of order against that bill that wasn’t overcome by a three-fifths waiver.

The veterans jobs bill was a priority of President Obama and was sponsored by Sen. Bill Nelson (D-Fla.), who is in a tough re-election fight right against challenger Rep. Connie Mack (R-Fla.).

The COLA rate in Murray’s bill would match the annual increase provided to Social Security recipients and is based on the Bureau of Labor Statistics Consumer Price Index.

“My hope is that whichever senator has decided to hold up this bill will at least come forward to own up to it,” Murray said today. “That way we can move forward to overcome their oppositions and get our veterans the support they need.”