Republican presidential front-runner Donald Trump holds a double-digit lead over his competitors in Oregon, according to a new poll by Portland-based Hoffman Research Group. Trump has 43 percent support in the poll, followed by Ted Cruz with 26 percent and John Kasich with just 17 percent support. Cruz and Kasich announced last weekend a joint effort to deny Trump the nomination. As part of the strategy, Kasich would clear a path for Cruz in the Indiana primary and Cruz would back down in Oregon and New Mexico. But both candidates have walked away from the arrangement since their campaigns' announcement....