State elections commissioner Elaine Manlove said voters had requested 6,410 absentee ballots in advance of Tuesday's primary, more than double the 2,624 that were counted in 2008, the most recent year in which Republicans and Democrats held presidential primaries in Delaware.

Tuesday's closed primary was limited to registered Democrats and Republicans.

Delaware Republicans are choosing between billionaire businessman Donald Trump, Texas Sen. Ted Cruz, and Ohio Gov. John Kasich.

Democrats are casting their votes for former secretary of state Hillary Clinton and Vermont Sen. Bernie Sanders.