Results of some of Tuesday's primary elections could determine who takes office in January, notwithstanding November's general election.
With Democrats far outnumbering Republicans in Delaware, winners of Democratic primaries could have the numbers stacked in their favor heading into November.
Six Democrats are vying to replace John Carney Jr. as Delaware's sole representative in the U.S. House.
Carney is running for governor and will face the winner of Tuesday's GOP primary between state Sen. Colin Bonini and retired Trooper Lacey Lafferty.
The Democratic primary for lieutenant governor also has drawn six candidates.
Other contests to be decided Tuesday include Republican and Democratic primaries for insurance commissioner, New Castle County executive and General Assembly seats, and an eight-way Democratic primary for Wilmington mayor.
Polls are open 7 a.m. to 8 p.m.