Democratic incumbent Sen. Brian Schatz is facing Republican Bob McDermott in the race to represent deep blue Hawaii in Washington.
In the run up to Tuesday's general election Schatz has run ads in local media but hasn't done much visible campaigning at home.
Last month, he traveled to Yuma, Arizona, to campaign for his Democratic colleague U.S. Sen. Mark Kelly who is in a tight race against Republican challenger Blake Masters.
McDermott has served 16 years in the state House of Representatives, where he is currently one of four Republicans and serves as assistant minority leader. He is a former U.S. Marine who served in Saudi Arabia during the first Gulf War.
McDermott has criticized Hawaii's congressional delegation for moving too slowly to push the Navy to close a massive World War II-era military fuel storage facility that leaked petroleum into Pearl Harbor's tap water last year.
Schatz has issued statements pushing the Navy to move swiftly to shut down the tanks and has touted work he's done to secure funding for the closure.
The Navy has said it expects to finish emptying the Red Hill Bulk Fuel Storage Facility by July 2024.
Schatz first joined in the Senate in 2012, when then-Gov. Neil Abercrombie appointed him to replace U.S. Sen. Daniel Inouye, who died while in office. He later won election.
He's served as the chair of the Special Committee on the Climate Crisis since 2019.