**What to Watch in the US’s Delaware Primary Elections**
As the last state primary election before the midterm elections approaches, voters in Delaware are preparing to head to the polls on Tuesday, September 19, 2026. Polls will open at 7 AM ET and close at 8 PM ET, allowing registered voters to cast their ballots in a series of key races that will shape the political landscape of the state and potentially influence national dynamics.
Delaware operates under a closed primary system, meaning that only registered party members can participate in their respective party primaries. For the Democratic primary, only registered Democrats may vote, while registered Republicans are allowed to vote in the Republican primary. Primary elections will only occur if there is more than one candidate from a party running for an office. Candidates running unopposed will automatically advance to the general election scheduled for November 3.
Among the notable races, Democratic US Senator Chris Coons is seeking re-election for a third full term. He faces three challengers: Jeff Appelhans, a history professor at the University of Delaware; Mary Louve, a naval architect; and Eric Hansen, a former business executive who previously ran as the Republican nominee in 2024 but is now contesting the Democratic primary under the name “E. No-Trump Hansen.”
On the Republican side, former state Senator Michael Katz and US Army Reserve Colonel John Shulli are competing for the nomination to challenge Coons in the general election.
In the race for the US House of Representatives, Democratic incumbent Sarah McBride, who made history as the first openly transgender member of Congress, is running unopposed in her primary. She is seeking a second term as Delaware’s sole representative. Meanwhile, three Republicans—Joseph Arminio, Earl Cooper, and John Whalen—are vying for the opportunity to face McBride in the November elections.
Delaware has seen a significant shift toward the Democratic Party since the 1990s. The state has not elected a Republican governor since 1988, nor has it seen a Republican win a US Senate seat since 1994 or a US House seat since 2008. As of September 1, 2026, Delaware had approximately 808,000 registered voters, with about 331,000 registered as Democrats and roughly 199,000 as Republicans.
As the primary elections unfold, all eyes will be on the outcomes, particularly in the Democratic races, where incumbents are expected to maintain their positions. However, the competitive nature of the Republican primaries could set the stage for a more dynamic general election landscape.
Voter turnout and engagement will be critical factors to watch, especially in a state that has consistently leaned Democratic in recent years. The results of these primaries will not only determine the candidates for the upcoming general election but may also provide insights into the broader political trends as the nation approaches the midterm elections.