Obama was keeping such a low profile that his presidential campaign would not say where he is staying, and local officials were also mum. An official at Government House in the capital, Charlotte Amalie, would only confirm that Obama was in St. Thomas, the most populated island. Tourists said they spotted him on the beach Sunday.

The Illinois senator is popular in the U.S. Virgin Islands, which in February gave him three delegates in the race for the Democratic nomination. Rival Hillary Rodham Clinton did not win a delegate at the caucuses. Six superdelegates will go to the August national convention; four have backed Clinton and two have endorsed Obama.