I'd really love to see some third party have some of the Democrats or Republicans in Congress who are closer to their views defect to them. It could happen, and they would continue to be re-elected, should the be popular in their state.
Who do you think are the most likely to do that?
Obviously a centrist/moderate party would be the most likely to peel people from both sides... but liberal Republicans and conservative Democrats rarely agree on the same issues... in fact, they're the most diametrically opposed members of Congress. Sure, there are some "Moderate Heroes" who could form a "Moderate Hero" party... but I don't see that happening.