Whoever emerges as the Democratic Party’s nominee for America’s presidency, Barack Obama or Hillary Clinton can count on the overwhelming support of the Caribbean Diaspora in fall election.

Black vote is disproportionately for the Democrats and immigrants from the Caribbean are no exception. If Barack Obama is the candidate, as increasingly seems to be likelihood, expect the Black and Caribbean turnout in favor of the Democrats to be even greater than in the past.

Whether for Mr. Obama or Mrs. Clinton, it is important that our vote is based not only on emotion. Caribbean people must leverage their ballots to ensure that in the end U.S. policy, especially under a Democratic presidency, is of value to this region.

We raise this matter out of concern for statements being made by both Mrs. Clinton and Mr. Obama, which have all the hallmarks of protectionism. That is potentially disastrous for the Caribbean, not least the Caribbean Community (Caricom).

Neither candidate has particularly addressed our section of the region, but has spoken with dissatisfaction about America’s global trade pacts, honing in specifically on the North American Free Trade Agreement (NAFTA), which covers the United States, Canada and Mexico. Essentially, NAFTA allows for the free movement of goods and services between the member countries. In terms of value it is perhaps the biggest trade agreement in the world.

But both Mrs. Clinton and Mr. Obama have been preaching that NAFTA is responsible for the loss of tens of thousands of manufacturing jobs in America, especially in mid-western states like Ohio, where they contested primaries on Tuesday. They have thought to outdo each other with tough talk and promises to renegotiate the agreement on winning the presidency.

“I think we should use the hammer of a potential opt-out as leverage to ensure that we actually get labor and environmental standards that are enforced,” Mr. Obama remarked in an Ohio debate. Mrs. Clinton has said forthright that she will scrap the agreement if Canada and Mexico don’t agree to a renegotiation.

These positions may, in part, be driven by the support of trade unions for the Democratic Party and the need for candidates to pander to voters in the rust belt regions, as a memo by a Canadian official claimed to have been the private assurance of an Obama adviser.

We are not sanguine. Indeed, we worry that their posture may reflect a deeper protectionist instinct among the candidates. On the face of it, this issue may not be of great import to our region. Any such assumption is wrong.

For more than two decades Caribbean Basin countries have enjoyed a preferential trade agreement for most of their products. The region, under a separate arrangement, has preference for the export of ethanol to the United States. Since these agreements were first pushed through by former President Ronald Reagan, they have come under periodic attacks from Congress. And it is also true that the access NAFTA provides to Mexico has eroded the Caribbean’s advantage. An anti-free trade and unsympathetic person in the White House can only exacerbate the problem.

Caribbean leaders and West Indians in the U.S. Diaspora must tell Mrs. Clinton and Mr. Obama of our concerns.