Delaware voters will head to the polls on Tuesday, September 15, 2026, for the state’s primary election, which serves as the final contest before the November 2026 general election. The ballot features Democratic U.S. Senator Chris Coons seeking a third full term against three challengers, alongside an open race for state treasurer that marks the only statewide office without an incumbent this year.

Coons faces primary opponents Jeff Appelhans, Mary Louve, and Eric Hansen in the Democratic contest. Appelhans is a history professor at the University of Delaware, while Louve is a naval architect. Hansen, a former business executive, ran as the Republican U.S. Senate nominee in 2024 but is running as a Democrat in the 2026 primary. Hansen will appear on the ballot under the name “E. No-Trump Hansen.”

Campaign finance reports show a disparity in fundraising among the Senate candidates. Coons reported raising about $6.9 million for his campaign, while Appelhans reported raising about $1,500. Neither Hansen nor Louve has filed any campaign fundraising reports this cycle.

The race for state treasurer involves multiple candidates vying for the seat left by incumbent Democratic State Treasurer Colleen Davis, who is not seeking a third term. Investment manager Ted Lauzen, business owner Mike Miller, and economist Michael Smith are competing for the Democratic nomination. On the Republican side, former state Rep. Michael Ramone is unopposed for the nomination.

In other statewide races, Democratic U.S. Rep. Sarah McBride is unopposed in her primary as she seeks a second term as Delaware's sole representative in the U.S. House. State Attorney General Kathy Jennings faces primary challenges from attorney Dwayne Bensing and Patty Rickman, an advocate for victims of domestic violence. Republican David Graham is unopposed for the Republican nomination for state attorney general.

The Republican primary for U.S. Senate features a contest between former state Sen. Michael Katz and U.S. Army Reserves Col. John Shulli. Katz has raised about $159,000 for his campaign, while Shulli has raised about $118,000. For the U.S. House seat, Republicans Joseph Arminio, Earl Cooper, and John Whalen are competing for the nomination.

Voter registration data as of Sept. 1, 2026, shows about 808,000 registered voters in Delaware, including about 331,000 Democrats and about 199,000 Republicans. Only voters registered with a political party may participate in that party’s primary, meaning independent or unaffiliated voters may not participate in either the Democratic or Republican primary.

Early voting statistics indicate that as of Friday, September 11, 2026, about 30,800 ballots had already been cast in the Tuesday primary election. Of those early ballots, about 22,200 were from Democrats and about 8,500 were from Republicans. Polls close at 8 p.m. ET on election day.

Delaware counties release early and absentee voting results before releasing any results from in-person Election Day voting, with all three counties releasing almost all of their results from early in-person and mail voting in their first vote updates of the night. Automatic recounts are triggered in Delaware statewide primaries if the vote margin is less than 1,000 votes. For state legislative and county-level races, automatic recounts are triggered if the margin is less than 1,000 votes or less than 0.5% of the total vote, whichever is less.

Why It Matters

The outcome of these primaries will determine the candidates for the general election in a state where Democrats hold roughly 2-to-1 majorities in both the Delaware State Senate and State House. About half of Delaware’s 21 state Senate seats and all 41 state House seats are up for election in 2026. New Castle County, which includes Wilmington and Newark, is the most populous of Delaware’s three counties.

Historical trends show Republicans have not won the Delaware governorship since 1988, a U.S. Senate seat in Delaware since 1994, or the U.S. House seat in Delaware since 2008. In the 2024 state primary, about 86,000 Democratic primary votes and about 37,000 Republican primary votes were cast for governor. About 26% of Democratic primary voters and about 23% of Republican primary voters cast their ballots early in-person or by mail in 2024.

Timeline

Republicans have not won the Delaware governorship since November 8, 1988. Republicans have not won the U.S. House seat in Delaware since November 4, 2008. Also on September 10, 2024, about 37,000 Republican primary votes were cast in the Delaware state primaries for governor.

On that same date, about 26% of Democratic primary voters cast their ballots early in-person or by mail in the 2024 Delaware state primaries. In the 2024 state primary election, the AP first reported results at 8:22 p.m. ET. The last vote update of the night was at 11:30 p.m. ET with 100% of total votes counted. On November 5, 2024, Eric Hansen was the Republican U.S. Senate nominee.

What's New

Additional context identifies the University of Delaware as a university in Newark, Delaware, United States. Further background notes that the Delaware State Senate is the upper house of the Delaware General Assembly.