NEW : Ryan learned leadership at a young age , he says . Ryan opposed a controversial budget proposal , which aimed to revamp entitlement programs . Biden welcomes Ryan to the race , which he says will be ` ` clear choice ''
NEW : Ryan learned leadership at a young age , Romney says . Ryan wrote a GOP budget plan , which seeks to revamp entitlement programs . Biden welcomes Ryan to the race , which he says will provide `` clear choice ''