You may not know this, but the United States will have a presidential election in 2016 and there are candidates everywhere. The first two Republican presidential debates have already occurred, covering everything from Iranian nukes to whose image should appear on the $10 bill.

One vital issue, however, has received almost no attention: free trade.

In the months ahead, as primary voters consider their choices, we need to do a better job of forcing candidates in both parties to explain their views on a topic that impacts every one of us.

In the Sept. 16 Republican debate at the Reagan Library in California, none of the candidates mentioned trade. In two debates that have lasted a total ...