That has prompted efforts from Illinois' congressional delegation to kill the tax.
House Speaker Dennis Hastert, Illinois' two senators and most of the state's congressional delegation have signed letters urging U.S. Trade Representative Robert Zoellick to resolve the issue. Some lawmakers also have met with Mexican officials.
Representative Ray LaHood says hard-nosed trade talks are needed with Mexico.
Mexico's lawmakers imposed the 20 percent tax in January 2002. It has effectively shut down the portion of Mexico's soft-drink market that relied on U-S exports of the corn syrup