President Obama’s statement in support of same-sex marriage on Wednesday was a political expression of a personal belief.

It is significant to a nation divided on the subject. But its policy implications are limited, as the White House acknowledged. As a public policy matter, same-sex marriage is currently an issue that is decided by the states — a fact recognized by the president. His aides said that the president continues to believe that it should be.

South Carolina voters decided the matter with a constitutional amendment in 2006 that overwhelmingly passed in a statewide referendum. It stated that marriage is between one man and one woman.

Maybe the poll numbers demonstrate a national movement in public opinion regarding the issue, as L.A. Times columnist Doyle McManus asserts on our Commentary page. But it is hardly conclusive, as this week’s vote in opposition to same-sex marriage in North Carolina demonstrated .

Five states, including Massachusetts and New York have approved the notion.

Maybe Mr. Obama’s shift on same-sex marriage will change some minds on the topic. But it was more evidently designed to change some minds about his candidacy for re-election.

This is not to suggest that the president is insincere in his assertion, merely calculating in its potential advantage to him in an election year.

In a Gallup poll cited on Friday, 40 percent said it would affect how they vote, and the large majority of that group said they would vote against the president. Slightly fewer so-called “independent” voters said they would vote against him because of his statement.

Clearly, it’s a hot-button issue, and one that the president may have pushed to his own disadvantage.