Charles Wetherington is not a business lobbyist, he is quick to point out. He is president of BTE Technologies, a small manufacturer of health care and physical rehabilitation equipment based in Hanover, Md. In his day job, he adds, he is BTE’s chief engineering officer, chief manufacturing officer and the guy who “makes sure there is Coke in the Coke machines.”

Back in 2001, exports accounted for less than 2% of BTE’s business. Wetherington said his company then started working with the U.S. Commercial Service to expand its export business. By 2005, using its own revenue sources, BTE was able to expand exports to 15% of its business.

Because it was shipping high-value capital goods to overseas customers, BTE required payment either in cash or an irrevocable letter of credit. It was, Wetherington admits, an “onerous way to do business,” especially with smaller dealers.

BTE started working with the U.S. Export-Import Bank, using its receivables insurance to extend terms to dealers who can then provide their customers with favorable financing and allow them to pay the company back over time for sales.

“Since 2005, working with Ex-Im, our exports have rocketed to over 50% of our revenues for our products, 400% growth and our employment has nearly doubled,” said Wetherington. “I attribute the vast majority of this to that ability to make business easier to do with BTE through the Ex-Im Bank receivables insurance.”

Little wonder, then, that Wetherington calls the Ex-Im bank “mission critical” for his business and was in Washington today to lobby for reauthorization of the bank, whose funding will expire September 30, 2014. The bank, a New Deal agency created by President Franklin D. Roosevelt in 1934, provides U.S. exporters with credit and financing assistance. In FY 2013, the bank approved 3,413 transactions, 89% to small businesses, and approved $27 billion in authorizations.

Wetherington’s presence on Capitol Hill was part of a determined effort by the National Association of Manufacturers and other business groups to ensure that the bank’s funding is not eliminated by conservative Republicans and groups such as the Heritage Foundation that call the bank “corporate welfare” for big business.

“I have always believed that reauthorizing the Export-Import Bank is a bad idea,” said Rep. Jeb Hensarling, R-Tex., the powerful chairman of the House Financial Services Committee. He said he was “surprised but not shocked” when the bank requested a five-year reauthorization and an increase in lending cap by $20 billion to $160 billion. Noted Hensarling, “Only in Washington can a taxpayer-subsidized program whose only purpose is to pick winners and losers ‘fail upward’ by requesting more money.”

Critics such as Diane Katz of the Heritage Foundation accuse the bank of being “beset by mismanagement, dysfunction, and risk” and occupying a financing role that is already overwhelmingly provided by private investment.

But Daryl Bouwcamp says it takes people who have been “sweating, getting paid for export business to really explain where Ex-Im fits in.” Bouwcamp, senior director for International Business Development & Government Affairs at Vermeer Corp., an agricultural and industrial equipment manufacturer, has spent 24 years in international development, taking several hundred international business trips to more than 70 countries.

When it is competing for larger contracts, says Bouwcamp, Vermeer is often pitted against competitors from Germany, China and Japan. He said it is important not only to present high-quality products but to show potential customers a financial package that is competitive with that provided by other nations. Ex-Im Bank helps to ensure that.

Moreover, says Bouwcamp, many U.S. manufacturers produce niche products for specialized uses which present a “lot of challenges in financing our equipment to end users overseas.”

“Foreign banks don’t understand our type of equipment and therefore are not interested in financing local customers,” he explained. “They just don’t understand the residual value, what it does. They would much rather finance a car or a computer, something they understand.”

At the same time, U.S. banks face regulatory and legal prohibitions against asset-based lending in many overseas markets or find it too costly to oversee such loans. But Ex-Im can help to reduce that risk for U.S. banks by provide loan guarantees. Bouwcamp says Ex-Im has provided such a guarantee to Vermeer’s bank, Wells Fargo, which is allowing it to finance a deal for six trenching and road leveling machines that will be used in road construction in Saudi Arabia. The deal, expected to be completed this week, represents 36,000 hours of work for Vermeer.

“Without Ex-Im Bank, Wells cannot get involved in this one,” said Bouwcamp.

Sen. Joe Manchin, D- Va., and Sen. Mark Kirk, R-Ill., chairman and ranking member of the Senate Banking Subcommittee on National Security and International Trade and Finance, recently wrote that failure to reauthorize the bank would cause the U.S. to “lose over one million jobs and billions of dollars in exports. At a time when our economy’s recovery remains fragile, it would be foolish to weaken this shining example of a successful public-private partnership.”

NAM is not taking anything for granted in its efforts to see the bank reauthorized. “This is a top priority for the NAM,” says Linda Dempsey, vice president of International Economic Affairs for the manufacturing group. “America’s manufacturers cannot afford to unilaterally disarm in today’s global marketplace.”