Updated: 3:40 p.m.

Big retailers held off big banks in the Senate on Wednesday, when Sen. Jon Tester failed to secure enough votes to delay the reduction of debit card swipe fees.

The Senate voted 54-45 for the amendment, but the Montana Democrat needed 60 — a filibuster-proof majority — to prevail. The amendment would have delayed for a year Federal Reserve regulations designed to reduce the fees that banks charge retailers for processing debit card transactions.

Senate Majority Whip — and fellow Democrat — Dick Durbin (Ill.) led the charge against Tester’s amendment, saying it would amount to another bailout of banks, who count so-called interchange fees among some of their most profitable business lines. Durbin, who helped get the new fee limits inserted into last year’s financial regulatory overhaul, has estimated the vote would have handed the banks $1 billion a month. Tester countered that small banks would suffer, despite the fact that institutions with $10 billion or less would be exempt from any new regulations.

Despite the loss, Tester, who is up for re-election in 2012, laughed with colleagues on the Senate floor as it became clear that he would lose.

After the vote, Sen. Bob Corker (Tenn.), the Republican co-sponsor of the Tester bill, said he would not pursue the issue again.

“I think it is water on the bridge,” he said. “I’ve got other fish to fry, and we pretty well cooked this one.”

The new limits on fees are expected to go into effect July 21.

Several Democrats who voted to force a reduction of swipe fees during last year’s financial regulation debate flipped sides to support Tester and the delay. Durbin’s original swipe-fee amendment garnered 64 votes last year, and 56 of those supporters remain in the Senate.

Among those switching their votes were Sens. Michael Bennet (D-Colo.), Mike Crapo (R-Idaho), Mark Begich (D-Alaska), Kirsten Gillibrand (D-N.Y.), Charles Schumer (D-N.Y.), Kay Hagan (D-N.C.), Barbara Mikulski (D-Md.), Ben Nelson (D-Neb.), Debbie Stabenow (D-Mich.) and Jim Webb (D-Va.).

The tally is a culmination of a years-long lobbying fight that ended in an influence frenzy on Capitol Hill in the hours before Wednesday’s vote.

Webb, one of the most heavily courted Members over the past several days, patted a frowning Durbin on the back as he walked off the floor Wednesday.