Republican race is down to four main contenders.
Christie - Great in front of the camera. A much more moderate, establishment Republican. American Republicans could rally around him from the idea and stand point of he would destroy Hillary Clinton in debates. Would effectively use images of him and Obama in Presidential race to help win the swing vote.
Cruz - While to the moderates and the left he is an enemy, he is the smartest guy in the race. Argued cases in front of the Supreme Court, and would presumably pull a huge Hispanic vote. Organizationally he is light years ahead. Only candidate with staff in every county of the first three voting states. He's poised to pickup the Carson and Trump vote when/if they implode.
Rubio - Young, emotional and says all the right things. Vastly inexperienced and a poor manager of his own finances he literally KO'd Bush the other night. Has to be considered the front runner for the Republican establishment.
Trump - He needs to find a second and third issue to keep his supporters excited. Has put some work into a ground game in early states (is ahead of Rubio and Christie but way behind Cruz). I think there is part of the American public that would just love to see Trump debate Hillary and see what a Trump President would do. On the flip side the guy has a skin so thin that eventually he will totally implode or at least I presume he will.
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Candidates that have no shot
Bush - I literally can't find a Bush supporter in Iowa.
Fiorina - Had a good first two debates, not as good a third debate. She doesn't want to be President (she wants a book deal). The reason you know that is she has no real staff in any early states, and isn't making any grassroot efforts to build a ground game that will make her even competitive in Iowa, New Hampshire, and South Carolina.
Carson - Evangelicals like him because he is a nice person, but he isn't ready for the big time. As candidates trim and people get serious about looking at who they are voting for, I think we will see Evangelicals shift to Cruz. Same general ideas, but Cruz is hardened and a better policy candidate.
Huckabee, Santorum, Jindal - They would need a hail mary like Cruz imploding to even have a 1% chance to get the nomination.
Kasich - Has the record, and was really liked by most Republicans but has been grumpy and shown he is way more liberal than the primary base.
Paul - Has one guy ever destroyed a built in base faster than Rand Paul? If I was his dad I would make the call and tell him to end it, so we don't have to continue to see him on tv at debates.