Three farm leaders from Canada, Mexico and the United States on Wednesday sent a joint letter to their respective trade negotiators as talks began to renegotiate the North American Free Trade Agreement. The leaders called on trade representatives to streamline regulations and tackle trade barriers without disrupting the current flow of agricultural products among the three countries. Led by Zippy Duvall, president of the American Farm Bureau, the farm leaders held a signing ceremony and press conference in Washington, D.C., at the National Press Club to discuss the trade pact and reiterate, as they have for months, that the NAFTA talks should "do no harm" to the current agricultural trade flows across North America.Farm Bureau, the Canadian Federation of Agriculture and the National Agricultural Council of Mexico signed a letter stressing that trade negotiators should work to improve NAFTA, but not dismantle the trade pact.