A long-standing refugee welcoming center in conservative Idaho has found itself at the center of a campaign by adversaries seeking to force it closed, citing fears that the immigrants it hosts could include Islamist extremists. The backlash comes amid an uptick in anti-Islamic protests and advertising campaigns in the United States, including a high profile May rally outside an Arizona mosque that saw more than 200 protesters, some armed, berate Islam and its Prophet Mohammad. The newly formed Idaho group, whose 100 members plan a door-to-door information drive in July to win support for closing the refugee center in Twin...