WASHINGTON - Surrounded by military leaders in a Cabinet-style setting, Hillary Clinton on Thursday said she has "crossed the threshold" of foreign policy experience to serve as commander in chief. Supporters of rival Barack Obama fired back immediately, arguing that the former first lady's trips abroad hardly constituted a practice run for managing global crises. "She was never asked to do the heavy lifting" when meeting with foreign leaders, said Susan Rice, who was an assistant secretary of state in the Clinton administration and is now advising Obama. "She wasn't asked to move the mountain or deliver a harsh message or a veiled threat. It was all gentle prodding or constructive reinforcement. And it would not have been appropriate for her to do the heavy lifting."