(AP) — A bid by workers at Mississippi's Nissan Motor Co. plant for United Auto Workers representation could turn on a key voting bloc — 1,500 workers who are Nissan employees today, but were initially hired through contract labor agencies. The unionized Detroit Three agreed to gradually end second-tier wage scales in their most recent UAW contracts, and UAW Secretary-Treasurer Gary Casteel said there are limits on contract workers. Contract workers are part of what holds the costs down, and also make it harder for the company's employees to fight back, said Dan Cornfield, a Vanderbilt University sociologist who has studied unions. Today, all new production workers at Nissan's two assembly plants, plus its engine plant in Decherd, Tennessee, are initially hired through contract agencies, Bajaj said. The company says it began converting some workers at the three plants to its payroll in 2012, the same year the UAW publicly protested the use of temporary workers, although figures provided to the Mississippi state auditor show direct Nissan employees didn't begin to rise significantly until 2014. Bailey said that joining Nissan's payroll was great "morale-wise." Because she's a manager, she can't vote in the election, although she opposes the UAW.