There is increasing awareness that years of one-sided trade agreements are a significant factor in our economic problems, unemployment and the ever increasing cost of government welfare and programs that support lower income Americans. Involvement in an organization (the SPP) dedicated to the integration of the US, Canada and Mexico might not be reassuring to many voters.
More needs to be known about all the current candidates and eventual candidates.
Without starting a whole new discussion on trade here, I will say a couple of things: our biggest impediments to competitiveness are our own self inflicted liberal policies. Instead of slapping say a 25% tariff on imports, we would be better off to have tort reform and to roll back corporate taxes and the EPA and the EEOC and the OSHA and all of that. This could save a lot more than 25% and it would not cause a trade war and would not punish 100% of the American consumers for 10% of the workforce.
Our trade policy cannot overcome what the wage and government realities are in the rest of the world. They just cannot do it. I suspect Cain will more or less agree with this.
If you want a Perot or Trump style trade warrior, you will not like Cain.