The Senate on Wednesday failed to advance a bipartisan background check proposal that Democrats had hoped would be the core of any bill.

The background check legislation, championed by Democrat Joe Manchin III of West Virginia and Republican Patrick J. Toomey of Pennsylvania, received only 54 votes, six short of the 60 needed to clear a threatened filibuster. However, the measure does have 55 Senate supporters, given that Senate Majority Leader Harry Reid, D-Nev., changed his vote at the last minute to preserve his ability to call up the vote again.

In addition to Toomey, only three Republicans — Sens. Susan Collins of Maine, John McCain of Arizona and Mark S. Kirk of Illinois — voted in favor of the background check compromise.

Besides Reid, four Democrats voted against it, including Sens. Max Baucus of Montana, Mark Begich of Alaska, Heidi Heitkamp of North Dakota and Mark Pryor of Arkansas.

In the 24 hours leading up to the vote, President Barack Obama and former Rep. Gabrielle Giffords, D-Ariz., along with her husband, Mark Kelly, had personally lobbied on-the-fence senators or those who had declared themselves as “no” votes. But those efforts failed.