<P> Because of the cost of conducting a special election, most states hold elections to fill a Senate vacancy in conjunction with the next general election, while some states, such as Alabama and Texas, allow for special elections to the Senate to be held before a general election (similar to special elections to the U.S. House of Representatives, though special elections are on a state - wide basis). Special election can alter the balance of power in the Senate, as can temporary appointments . </P> <P> Prior to ratification of the Seventeenth Amendment to the United States Constitution in 1913, most state legislatures elected senators, as well as replacement senators . Some states empowered their governor to make temporary appointments until the legislature was in session . </P> <P> The Seventeenth Amendment now requires the governor of the state to issue a writ for a special election to fill a vacant Senate seat, but no timeframe is specified in the provision for when the special election is to be held . State legislatures may also empower the governor to fill a vacancy by a temporary appointment, until the winner of the special election is certified . The constitution does not set out how the temporary appointee is to be selected (eg., there is no federal requirement that the appointee be of the same party, as happened most recently in New Jersey in 2013), and the state legislature can legislate as to how the replacement is to be selected . </P> <P> As of 2010, Oregon, and Wisconsin do not empower their governor to make temporary appointments and require special elections; and Oklahoma permits its governor to appoint only the winner of a special election . Between 2004 and 2008, Massachusetts denied the power of the governor to appoint a replacement; in 2004, the Democratic - controlled legislature wanted to limit the power of the Republican governor (Gov. Mitt Romney) to appoint a successor to then - Sen. John Kerry if he were elected president that year . With the death of Sen. Ted Kennedy, the legislature chose to revert the rules to allow the Democratic governor (Gov. Deval Patrick) to appoint a temporary replacement Senator while awaiting the results of a special election to complete the existing term . Hawaii allows the Governor to appoint an interim Senator "who serves until the next regularly - scheduled general election, chosen from a list of three prospective appointees that the prior incumbent's political party submits". Alaska in 2004 enacted conflicting legislation and a separate ballot referendum law that took effect on the same day . It is uncertain if the Alaska governor may successfully appoint an interim Senator to serve until the mandated special election occurs 60 to 90 days after the vacancy happens . The ballot - approved law fails to specifically authorize the governor to appoint, though the legislative law does . </P>

Who calls a special election to fill a vacancy in the senate