The Export-Import Bank plays an integral role in helping small and large U.S. companies to compete in the global economy—and it's a key lifeline for a nuclear energy sector facing "economic headwinds," a former U.S. trade representative told CNBC.

Former U.S. Trade Representative Ron Kirk speaks during a reception in Washington in this Jan. 20, 2010 the photo. Tim Sloan | AFP | Getty Images

The export credit agency's authorization is set to lapse this year, making it a political football during a highly charged election cycle. Yet Ron Kirk, former Democratic mayor of Dallas and once America's chief trade negotiator, said the Ex-Im Bank plays a crucial role for the United States, especially in a global environment where other countries heavily subsidize key industries.

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"It is such a needed tool to help American exporters maintain their competitiveness," said Kirk, who added that Ex-Im Bank is especially important for companies that are feeding an international boom in demand for atomic energy.

"'Made in America' is one of the best value propositions in the world, whether it's a nuclear reactor or a car," said Kirk, who is now co-chair of the Clean and Safe Energy Coalition, a nuclear energy advocacy group. Ex-Im Bank feeds credit to a host of U.S. companies, some of which are involved in energy-related projects abroad. Last month, the agency financed $65 million in direct loans to two wind turbine projects being constructed in Peru by the U.S. arm of Siemens Energy.

Nuclear power was the U.S.'s gift to the world," Kirk said. "How ironic would it be that, because of a largely philosophical debate, we would take this technology out of commission? Ron Kirk Former U.S. trade representative