"NAFTA has been overwhelmingly beneficial for the vast majority of farmers and ranchers across the US for decades,” said Mr Shawcroft in testimony on behalf of the American Farm Bureau Federation.

US agricultural exports to Canada and Mexico have quadrupled, from $8.9 billion in 1993 to $38.1 billion in 2016. Although the benefits from NAFTA are clear and many, there are reasons to reform and update the agreement, Mr Shawcroft said.

NAFTA renegotiations present a prime opportunity to address challenges fruit and vegetable farmers have faced with Mexico, as well as a chance for dairy, row crop and wheat farmers to settle issues with Canada.

"A modernized NAFTA should at best eliminate, at worst reduce, barriers to trade that keep our farmers and ranchers from having a level playing field with our neighbors," Mr Shawcroft said.

Farm Bureau priorities for a modernised NAFTA include:

• Updated, science-based sanitary and phytosanitary rules;
• Improved dispute settlement procedures for fresh fruits, vegetables and horticultural products;
• Eliminated or reduced Canadian tariff barriers to dairy, poultry eggs and wine, as well as the recently implemented barriers to ultra-filtered milk;
• Addressing the misuse of geographical indicators; and
• Developing a consistent, science-based approach to biotechnology.

"A modernised NAFTA will not only help expand market opportunities for US farmers and ranchers in the near term," said Mr Shawcroft.

"It would also set a foundation for future trade agreements by establishing market-driven and science-based terms of trade and dispute resolution that will directly benefit the US food and agriculture industry."