Radio Iowa: Republican Sen. Chuck Grassley and former Iowa Gov. Tom Vilsack, a Democrat, joined forces Tuesday in the nation’s Capitol — making the case for ratification of the USMCA, which would replace the North American Free Trade Agreement. Vilsack, who served eight years as U.S. secretary of agriculture, is now president and CEO of the U.S. Dairy Export Council. “I have a simple message for the committee: Exports matter to American food and agriculture industry,” Vilsack said. “Thirty percent of all agricultural production and 20% of all agricultural income is directly related to exports.”