On the merits, the case for closing the Export-Import Bank is a slam-dunk. This has made life difficult for the bank’s supporters, especially since the bank will permanently close on June 30 unless Congress reauthorizes its charter. So they are switching to politics.
One of the top items on Congress’ agenda is Trade Promotion Authority (TPA), which despite some drawbacks, would make international trade a little freer than it is now. Seeing a point of entry, Ex-Im supporters tried to tie Ex-Im reauthorization into the TPA bill. This way, a Senator who opposes Ex-Im might have to hold his nose and vote for it anyway, since it would be part of the larger TPA bill he supports.