Airplanes, software, seafood and agriculture are four of the many reasons Americans have a political interest in international trade. We need a president who will promote reasonable rules rather than resentments and restrictions.

Regarding trade, the choice between President Obama and Mitt Romney is troubling. It is also uncertain because on this issue, Americans have learned not to believe anything their candidates say.

Obama ran in 2008 appealing to resentment of trade, as did all the Democratic contenders that year.

When Obama came out against the North American Free Trade Agreement, promising to renegotiate it, his economic adviser Austan Goolsbee whispered to the Canadians: Don’t believe what we say. It’s an election.

Mitt Romney has said flatly he is for free trade.

Then again, Romney has also promised that on his first day in office he will label China a currency manipulator, forcing China to negotiate over the value of its money.

He is running for office, and it’s a good bet some of these stances will be moderated if he gets the chance to govern.

Still voters must pay attention and vet the candidates.