Del. Code tit. 14, § 1915

If in any year, not less than 2 months before the date of the regular school election, a number of voters, not fewer than 25 percent of the number of qualified voters of the district, shall demand over their signatures that an election be held, the board of education shall call an election as provided in § 1903 of this title, and the result of such election shall be binding until another election.