If Obama wins re-election -- and I think the chances of that improve daily without a quick winnowing of the Republican field, followed by a refocusing of Republican fire on the real target, rather than eachother -- this overly-drawn-out and acrimonious primary will be to blame.
The media and the Democrats (but I repeat myself) are loving it, but it is bleeding the right of resources and energy and it's "diminishing the brand," as Krauthammer points out. Paul and Gingrich have had as much impact as they are going to have. If they stay longer, it's just a selfish ego trip that assists Obama. Santorum has peaked; his "conservative" credentials are even more iffy than Romney's; he drags the party into a social issues quagmire that will kill it (which is where the media and the liberals want the battle fought); and he just doesn't have the horsepower to win.
Romney isn't ideal but he has been winning, with respectable levels of support from Tea Party people and true conservatives. Doubts about his conservative bona fides and "electability" are being exaggerated and amplified by the horserace-loving media. If the Right tries to make perfect an enemy of the good, it will lose and we'll have four more years of Obama.
Any questions? Send them to Krauthammer.