Fred P. Hochberg, chairman and president of the U.S. Export-Import (Ex-Im) Bank, speaks during a House Financial Services Committee hearing on the Ex-Im Bank reauthorization in Washington, D.C., U.S., on Wednesday. The U.S. agency that helps foreign companies buy American-made products is facing the biggest test in its 80-year history as House Republicans press to shut the Ex-Im Bank. (Andrew Harrer/Bloomberg News)

It was just a week ago that the debate over keeping the doors open at the usually little-noticed Export-Import Bank burst into the spotlight, the latest flash point for a divided Republican Party. But the topic has been keeping corporate lobbyists and trade associations busy for years.

The Aerospace Industries Association, whose members — including Boeing, the bank’s biggest beneficiary — rely on its loan guarantees to help sell their products abroad, has, since 2008, listed the bank among the issues it lobbies on, according to federal disclosure reports. Caterpillar, another exporter that benefits from the bank’s loans, lobbied on the bank in 2009.

In fact, according to a new study by the Sunlight Foundation, a D.C. nonprofit that advocates for greater government transparency, at least half of companies and organizations that have been most active on the issue reported lobbying on the bank every year since 2010.

Delta Air Lines, perhaps the bank’s most outspoken corporate critic, started lobbying on the issue in 2011. (The airline isn’t wild about the way the U.S. government agency helps finance purchases of wide-body aircraft by its foreign competitors.)

That’s the year things started to get more serious, ahead of the bank’s most recent reauthorization in 2012.

“There was a bigger level of critique than we had seen” in past debates about renewing the bank’s charter, said Linda Dempsey, vice president of international economic affairs at the National Association of Manufacturers.

In May 2012, a vast majority of House Republicans ended up supporting renewal, with 147 voting yes and 93 opposing it. NAM, the U.S. Chamber of Commerce and big exporters kept working on the issue.

And now — after Rep. Kevin McCarthy (R-Calif.), the incoming House majority leader, signaled his opposition to the bank, and an energized tea party wing of the GOP has seized on it as an example of crony capitalism — they’re glad they did.

Faced with complaints that the bank is a form of corporate welfare whose work would be better left to the private sector, the manufacturers association is spearheading a big corporate push, arguing that its renewal is key to creating jobs and ensuring American competitiveness.

In December, NAM took representatives from large companies and their suppliers to the Hill to help explain to House freshmen — who haven’t voted on the issue before — how the bank works.

The group organized a House Ex-Im lobby day in early May, and another on the Senate side on June 5. Then, three weeks ago, during a “Manufacturing Summit,” hundreds of NAM members made the case for the Ex-Im Bank on the Hill.

NAM’s top political strategist, Ned Monroe, wouldn’t talk about how the many business groups involved in the fight are coordinating their efforts. But he acknowledged that his group recently “re-engineered” its Ex-Im Bank campaign. “The political dynamics change with every single Congress and every single issue,” he said Friday.

Last week, the NAM-led coalition sent a letter to Congress from 865 organizations that support the bank, and the group announced that it had hired a few political heavy hitters to help make their case, including Richard A. Gephardt, the former House Democratic leader, and Haley Barbour, a former Mississippi governor and Republican National Committee chairman.

The choice of Barbour was an especially interesting one. That same week, he played a big role in helping Sen. Thad Cochran (R-Miss.) fight off a tea party challenge. Is he really best placed to help win over the same crowd when it comes to the bank?

“This is not about our legislative opponents,” Monroe said, not quite embracing the question. “This is a jobs issue. This is an opportunity to find out who is the best messenger.” (Barbour, a well-connected lobbyist, also counts Caterpillar among his clients, though he doesn’t list the bank among the issues he works on for the company.)

On the other side, much of the push is coming from conservative groups such as the Club for Growth.

Of course, NAM isn’t alone in making the case for the bank. Lots of exporters are tapping their own lobbyists, and some of them have been encouraging Hill staffers to use a feature on the Ex-Im Bank’s Web site that shows the dollar value of exports the bank has agreed to finance in each state and congressional district.

The Aerospace Industries Association is stepping up its effort, too, with tough messages about jobs and American competitiveness. At a House Financial Services Committee hearing Wednesday, the group scored big when Fred P. Hochberg, president and chairman of the bank, held up a full-page ad it had placed in Politico, arguing that China, Russia and France all have their own versions of the bank, and shuttering the U.S. one would send thousands of jobs overseas.

The Chamber of Commerce is playing big, too, and, like NAM, promises that its members and affiliates will use the July 4 congressional recess and the month of August to show lawmakers how important the bank is to businesses in their districts.

As NAM’s Monroe put it, “at the end of the day, the issue that matters most is hearing from constituents.”

With the Ex-Im Bank’s current charter set to expire on Sept. 30, they’ll find out soon if that’s enough.