They should drop out of the race. Everyone knows that by having 6 candidates in the race greatly benefits the front runner, in this case Mitt Romney. If Newt, Santorum, perry and hunstman dropped out of the race it would be down to Mitt and the 2nd place challenger in most polls, Ron Paul. I truly believe that people would rally behind Ron Paul and his ideas. He provides a breath of fresh air as he does not come from the establishment!
I think attacking Romney is fine, but we should be attacking and focusing on obama. He's the man we are really trying to defeat.