When Mitt Romney unleashed a barrage of criticism against his party's front-runner, he began with the economic argument against Donald Trump. He's not alone in these claims: Many economists are also expressing their concern that the real estate magnate's policies could lead to a global recession.

Romney charged that Trump "would be very bad for American workers and for American families." But Trump's tax plan bears many similarities with other GOP hopefuls in that it would reduce the marginal rates for many individuals and businesses. Instead, it's his propositions for America's place in the global economy that are raising eyebrows.