By Jonathan Landay and Ted Hesson WASHINGTON (Reuters) – A lack of flights and the search for a new U.S. reception center are among the hurdles facing the White House as it races to speed up the evacuation of at-risk Afghans from their homeland, according to a senior U.S. official and others familiar with the new plan. Other obstacles include difficulties in obtaining passports and an affordable housing shortage in the United States, they said. The plan’s goal “is just to make this more enduring and less of an emergency operation,” the senior U.S. official said in describing the revamp, reques…