NEW : Barack Obama criticizes Congress , statement from John McCain . McCain 's campaign says Obama `` failed to lead '' VP candidates ' debate on Iraq and Afghanistan. Joe Biden , Sarah Palin spending much of the week in debate prep mode .
NEW : Barack Obama criticizes Congress , statement from John McCain . McCain 's campaign says Obama `` failed to lead '' VP candidates ' debate is Thursday in St. Louis , Missouri . Joe Biden , Sarah Palin spending much of the week in debate prep mode .