The battle of exporters vs. importers heated up today as a consortium of 16 exporters including GE, Caterpillar, Dow, and Pfizer fired off a Letter to Congress Backing a Levy on Importers.

The heads of GE, Boeing, and other large corporations have warned that the US may not have another opportunity to revamp its tax code for 30 years if it misses out on a chance to do so now amid uproar over a proposed import tax.

In a letter to Congress, 16 chief executives from exporters including Caterpillar, Dow Chemical, and Pfizer issued their strongest statements of support yet for the import tax, which retailers, oil refiners, and other importers are fighting to kill.