The Obama administration stood solidly against closing the US-Mexico border Thursday, with Vice President Joe Biden calling the option "a monumental undertaking" with only limited benefits now that the swine flu virus has spread to many states and forced roughly a hundred school closures. Biden and Dr. Richard Besser, acting director of the Centers for Disease Control and Prevention, reinforced the government's stance on a border closing a day after President Barack Obama ruled it out during a prime time televised news conference, saying such a step would be tantamount to "closing the barn door after the horses are out." Biden told interviewers on morning network news shows he sympathizes with parents worried about the spread of the disease in the United States, but said that shutting down America's borders would be far more complicated - and would carry potentially great consequences - than simpler steps like closing schools and canceling or postponing public meetings. Biden also reiterated on Thursday the advice the administration has been eagerly dispensing: "A parent whose child's school is closed out of a precaution or because there's been a confirmed case of flu should not take child then to a day care center. They're going to have to take them home."