The governor and Secretary of State Sam Reed said the state is required to hold a vote to fill a vacant seat under the U.S. Constitution. Inslee resigned last month to run for governor

OLYMPIA — Washington will hold a special election in November to replace former U.S. Rep. Jay Inslee for just one month — an election expected to be confusing for voters, burdensome for candidates and costly for the state.

Democratic Gov. Chris Gregoire and Republican Secretary of State Sam Reed said Monday the state is required to hold a vote to fill a vacant seat under the U.S. Constitution. Inslee resigned last month to run for governor.

The November election will be particularly confusing to voters because Congress also is transitioning to its new district boundaries. The special election will be focused on the old 1st District Inslee represented. Voters will also decide who will represent the new 1st District.

Gregoire and Reed said they had explored the possibility of a special election under the new 1st District boundaries to keep things simple. But that would have meant some residents would briefly have two representatives in Congress while others would have none.

The candidate chosen to replace Inslee will serve just one month until the new person is seated in January. Reed’s office says the election will cost the state an extra $770,000.

Reed said the state will work to educate voters about the confusing ballot. Ballots for the primary election would be due Aug. 7, while the final vote would take place during the regular general election in November.

The filing fee for the race is about $1,700.

Gregoire said the election also will be difficult for candidates. A candidate who wants to run for both 1st District slots would have to manage separate campaigns to collect donations and account for spending.

“Wow. That’s a challenge,” Gregoire said.

Inslee represented the 1st District, which currently includes Seattle’s northern suburbs and Bainbridge Island, starting in 1999.