LAS VEGAS (AP) — When Marco Rubio attends his 44th birthday party and fundraiser at the home of the host of the "Pawn Stars" reality show Thursday, it won't be his first birthday in Las Vegas. The Cuban-American son of South Florida spent part of his childhood in Las Vegas, from 1979 to 1985, where he joined the Mormon church, became a fierce union supporter at a tender age and grew alienated from his Cuban-American peers before returning to Miami for high school. In these formative years, Rubio impressed schoolmates and neighbors as a curious and driven boy who talked too much in class and showed early signs of the policy wonk and competitive player he would become. [...] many casino workers don't vote in the Republican caucuses and Rubio must distinguish himself in a large pack of rivals. Nick Phillips, political director of the Clark County Republican Party, said he has only recently begun hearing about Rubio from activists. Rubio, then 8, his parents, younger sister Veronica and grandfather moved into a four-bedroom house on a cul-de-sac at the northern edge of town. In his memoir, "An American Son," Rubio recounts a wholesome neighborhood atmosphere with afternoon games of cowboys and Indians, Cub Scout trips and church events. Back in Nevada, cousin Mo Denis became a Democratic state senator.