I think this is the time to see some changes in the middle. Michael Bradley just didn't do the job in the group matches, and the lack of overall possession has made life difficult. I'd take the gamble of playing Mix Diskerud as an attacking CM in front of Beckerman and Jones, with Dempsey as a lone striker, two wingers (probably Zusi and Bedoya), and the normal back four.
Or perhaps Jones as an attacking CM in front of Beckerman and Cameron, who has some experience in a holding role.
Edit: Or maybe Dempsey in the middle with Beckerman and Jones, with Johanson up front.