Mitt "Mittens" Romney.
Mitt Romney is a politician and a Republican. As such he has spent the past 2+ years positioning himself as a credible conservative and counterpoint to Obama so he could secure the GOP nomination this time round. Many Republicans do not like him because he is 1. a Mormon and 2. moderate.
The first thing that must be stated about Romney is that his positions have changed so much that one can find evidence on many issues showing that Romney both supports and opposes them. That said...
He has been on the record in support of gay rights and abortion. His big accomplishment as governor was a universal health care bill that looks (almost exactly) like Obama's, and which he used to suggest as a national model until that position became untenable in the present GOP/tea party atmosphere. He supports and believes in science (at least he used to), including evolution and anthropogenic climate change. He has supported cap and trade as a mechanism to deal with greenhouse gasses. He has supported a path to citizenship for illegal immigrants.
As far as foreign policy it is more difficult since he never had to deal with it as governor, but he seems to be somewhat less militant than Bush was, but that would put him slightly to the left of Obama, so meh.
Romney's economic policy positions are what most distinguish him from Obama. Even in this, however, the most meaningful is that Romney--himself a rich person living on capital gains from his wealth--doesn't want to tax himself and other rich people more heavily. This would be a more dangerous position if it wasn't for Obama's completely stupid "pledge" to not raise taxes on people making under $250k/year which he seems to consider extremely important (I suppose because he remembers how hard it was to get by on the $173k/year US Senator salary).
The other Romney position that would make a difference is the GOP "all regulations are the work of the devil" position that has little basis in fact. Mostly this is a talking point, since the only regs that they actually seem intent on eliminating are those for the financial industry and polluters. If they were to roll the former back, it would be bad, but the regs that got put in place are so weak that eliminating them won't be disastrous. Wall Street is plenty capable of destroying our economy again as things stand now. Making it slightly easier can only help push Republicans out of favor faster. Eliminating the EPA is a bigger problem, but, again, there really isn't anything in Romney's past that would indicate this is a real possibility.*
*Of course there was nothing in Obama's past that indicated he would be as oppressive of civil rights as Bush was so hmm...