WASHINGTON — President Obama signed a bill on Wednesday that extends the life of the Export-Import Bank through 2014, ending an unexpectedly fierce political fight over an institution dedicated to financing American exports abroad.

Speaking at the signing ceremony to an audience filled with owners of small businesses, Mr. Obama said the reauthorization of the bank was critical to leveling the playing field with China and other countries, which provide similar credit to their export industries.

“We’re helping thousands of businesses sell more of their products and services overseas,” the president said, “and in the process, we’re helping them create jobs here at home. And we’re doing it at no extra cost to the taxpayer.”

Mr. Obama paid tribute to Congressional leaders who brokered the deal to preserve the bank, which was in jeopardy after Tea Party-aligned conservatives in the House and Senate seized on the need for reauthorization as a chance to mothball an agency they say is a purveyor of welfare to big corporations like Boeing and Caterpillar.