Ex-Im, as it's known in Capitol Hill parlance, provides cheap loans to foreign companies who want to buy U.S.-manufactured goods, particularly Boeing airplanes. The agency has limited macroeconomic significance, but its very existence has ignited a holy war within the Republican Party, where hardliners view the bank as an exercise in corporate welfare.

Ex-Im's formal authorization expires Sept. 30, the same date congressional funding for the entire federal government runs out. If the Democratic-led Senate insists on reauthorizing and funding the bank, the Republican-controlled House can reject the measure, and shut down the government just five weeks before the November elections.