Mitt Romney will win the GOP presidential nomination because there is enough difference between Romney and the rest of the field. Mitt Romney will lose the general election in the fall because there is not enough difference between himself and the current occupant of the White House.
Senator John McCain lost to Mr. Obama in the 2008 general election in large part because there was no compelling reason to vote for him. He inherited the nomination for finishing second in the GOP in the previously contested GOP race. Mr. Romney finished second to Mr. McCain in 2008's GOP contest. The hierarchical GOP will nominate a centrist candidate like McCain and Romney but they will not elect him.
The prior wisdom of American politics was you would run from the Left (Democrat) or the Right (Republican) and then govern from the center (American). Now, you run from the Far Right or the Anemic Left and govern barely, with a Far Right Congress and a Far Left Judiciary (so far). The Roberts court Far Right actions will be ameliorated by Mr. Obama's current standard bearers and the ones to come during his second term.
When Mr. Romney's opponents attack him now, it is from the Left. He was a successful Venture capitalist, meaning people got fired and wealth got transferred. People may look with envy on the rich but not affection. Mr. Romney has too many negatives for undecideds. He can win but it is not likely. Please note the difficulty he is having with winning the nomination. He is not Republican enough for the Republicans, certainly not Democrat enough for the Democrats and not likable enough for the Undecideds. He can still win if the economy tanks during the next six months.
Who wants that?
Probably not even Mr. Romney.
Opinions expressed here are mine alone.