Four St Peter Port parishioners have put themselves forward for election, but with five seats up for grabs there will be a vacancy.
Parish constable Dennis Le Moignan said it was the first time there had not been enough candidates.
He blamed a "lack of interest" and little understanding of the role.
However, others believe criticism of the douzaine over the appointment of a town centre manager may be behind the lack of volunteers for the unpaid position.
Shane Langlois, chairman of the Douzaine Council, said: "Obviously there's been a lot of controversy over the town centre manager, but that's just guesswork."
He said another possible reason for a lack of interest from parishioners was because the parish system was confusing, although the picture around the rest of the island was more encouraging.
Mr Langlois said: "There are far more contested elections than I've ever seen... it's very unusual and encouraging. There's normally not more than one or two."
He has called for an end to electors' meetings where elections are uncontested - as currently parishioners can vote for ballots to take place - describing them as unnecessary.
Mr Le Moignan said the St Peter Port Douzaine would have to advertise the fifth position again and hold another election at a later date.
He said there was also a chance the election could be thrown out at the electors' meeting and it would not go ahead until another candidate comes forward.
A "lack of interest" in parish politics is being blamed for a shortfall in the number of candidates needed to serve in a Guernsey parish.