SIOUX FALLS, S.D. (AP) — Primary voters will decide whether to add a new requirement to South Dakota’s constitution that will make it more difficult to pass ballot measures that raise taxes or expend significant government funds. The proposal creates a showdown over direct democracy in a state where voter-initiated laws were pioneered but Republicans pride themselves on levying minimal taxes. The proposed constitutional amendment, which will appear as Amendment C on ballots, would place a 60% vote threshold on citizen-initiated ballot measures that raise taxes or spend more than $10 million within five years of enactment.