Del. Code tit. 15, § 7321

Whenever a vacancy shall happen by death, resignation or otherwise in the office of Senator from this State in the Senate of the United States, the Governor may make a temporary or ad interim appointment from among the qualified electors of this State of some person to fill such vacancy until the same shall be filled at the next ensuing general election in the manner prescribed by law. The office of such temporary appointee shall terminate upon the election, under this title, of a Senator from this State in the Senate of the United States to fill the vacancy.