Factbox: Key issues in the NAFTA renegotiations

RULES OF ORIGIN: NAFTA says in order for a good to be traded duty-free within the three countries, it must contain a certain percentage of North American content, which differs for various products. The rule of origin is most contentious in the auto industry; cars must contain at least 62.5 percent American, Canadian or Mexican content. The United States wants to increase the content threshold for NAFTA goods in a bid to return manufacturing jobs to the United States, and the auto industry has conceded that the rules should be updated to account for auto components that did not exist when the original deal was signed. Canada has said it is prepared to discuss some strengthening of rule of origin in the auto sector, but that any change must apply equally to all three countries. Mexico is willing to look at strengthening rules, but warns that going to far will make the region less competitive.

DISPUTE RESOLUTION: The United States has sought to ditch the so-called Chapter 19 tool, under which binational panels hear complaints about illegal subsidies and dumping and then issue binding decisions. The United States has frequently lost such cases since NAFTA came into effect in 1994, and the mechanism has hindered it from pursing anti-dumping and anti-subsidy cases against Canadian and Mexican companies. Washington also argues that Chapter 19 infringes on the sovereignty of its domestic laws. Canada has said Chapter 19 can be updated, but said a dispute settlement mechanism is its "red line" and must be part of any updated NAFTA. Mexico also says dispute settlement mechanisms are a vital part of the deal to give investors security.

SUPPLY MANAGEMENT: Quotas are a feature of NAFTA in several agricultural commodities including dairy and sugar, but Washington is seeking to eliminate non-tariff barriers to U.S. agricultural exports. Most notably, U.S. President Donald Trump has called Canada's restrictions on dairy imports a "disgrace." Although dairy was excluded from the original 1994 deal, the United States is seeking to eliminate non-tariff barriers to its agricultural exports.

CURRENCY MANIPULATION: The United States is seeking a provision to deter currency manipulation. While Washington wants a mechanism to ensure the NAFTA countries avoid tinkering with exchange rates to gain a competitive advantage, neither Canada nor Mexico is on the U.S. Treasury's currency manipulation watch list. Critics say the U.S. demand is an attempt to get currency manipulation into a global trade agreement to establish a precedent with other trading partners, including China.

GOVERNMENT PROCUREMENT: The United States is pushing for national, state and local governments in Canada and Mexico to open up their tender processes to U.S.-made products but at the same time is defending existing "Buy American" procurement laws. The Buy American provisions have blocked the use of Canadian steel to build U.S. bridges, and Canada is pushing for a freer market for government procurement. Mexico says it expects government procurement, already included in NAFTA, to be part of the renegotiation.

INVESTOR-STATE DISPUTE SETTLEMENT: The United States has proposed minor tweaking of the NAFTA Chapter 11 provisions, which are designed to ensure firms that invest abroad receive "fair and equitable" treatment by foreign governments. As with Chapter 19, opponents of the provisions argue they infringe on sovereignty which benefits multinational corporations. Canada wants to update the mechanism to allow governments to regulate in the interest of the environment or labor, as in the Comprehensive Economic and Trade Agreement that Canada recently negotiated with the European Union.

(Reporting by Andrea Hopkins)