Philip Klein ponders one of the most irresistible counterfactuals of the primary:

When Romney decided to seek the presidency for the second time, his moderate to liberal record in Massachusetts was bound to trigger a challenge from the right and set up a showdown, framed in shorthand, as the establishment of the party versus the conservative base. Had Palin been in the race as the conservative alternative, it would have been very difficult for Romney to attack her given the passionate following she has among many conservatives, because he wouldn’t want to risk alienating them. Even if he had ultimately triumphed after a brutal primary fight, a lot of her loyal supporters would have found it difficult to bury the hatchet for the general election.

By contrast, Santorum came into the race with a very small following and was polling in the low single digits early on. Only when a number of other hopefuls fizzled did he emerge as the conservative alternative to Romney. Don’t get me wrong, as I wrote earlier, I think Santorum raised his profile over the course of the race and proved to be a tenacious campaigner. But the point is that Santorum’s support was as much about him being a vehicle for those who wanted to stop Romney than it was about a groundswell of support for him personally. His defeat is a disappointment to his supporters, no doubt, but less likely to sting as badly for as many people as a Palin defeat would have. Now that the primary is over, it will be a lot easier for Santorum voters to get behind Romney in the general election than it would have been for Palin given her built in fan base.

Yeah, Santorum was always chiefly a “Not Romney” but Palin would have been Palin, to the point where if she had run I wonder if Mitt would have ended up as the “Not Palin” instead of her ending up as the “Not Mitt.” Hard to believe she wouldn’t have given him a much tougher race than Team Sweater Vest: She would have appealed to the same blue-collar and evangelical Republicans as Santorum did while almost certainly being better funded thanks to her supporters’ enthusiasm. The debates would have been an opportunity for her to make inroads with centrists who dislike Romney but were leery of her grasp on policy: Had she done well in those, she could have turned around some doubters while stealing Newt’s thunder as the anti-media candidate. If she had then gone on to win Iowa instead of Santorum, who knows how that would have scrambled the race in South Carolina? Maybe she wins there too as Gingrich ends up as an afterthought, and then suddenly there’s all-out war in Florida as Romney and his Super PAC flood the state with attack ads to blunt her momentum — triggering precisely the sort of resentment among her supporters that Klein imagines. Romney probably wins that hypothetical race simply because of his financial and organizational advantages and the premium placed on electability by primary voters, but I think it’d be a closer call than Romney versus Santorum was. And whatever the outcome, there would have been more bitterness at the end.

I always thought she’d run this time just because it was the best chance she’s likely to have. She was the VP nominee in the last election and less than three years out of office as governor, Romney was a weak frontrunner and the next generation of GOP stars wasn’t quite ready, Obama was a vulnerable incumbent presiding over a sluggish economy, and the tea party was looking for a candidate whom they could rally behind to show some muscle at the presidential level. None of those things is likely to be true the next time Republicans hold a competitive primary. Unless she challenges Mark Begich for Senate in 2014, I’m not sure what the path back is.

Update: Via Twitter, Ian from Conservatives4Palin catches me in a contradiction. Didn’t I once write that “she did the smart thing by staying out”? Yep:

She did the smart thing by staying out. Just yesterday, CBS found that three out of four Republicans didn’t want her to run compared to just 23 percent who did. Her favorable numbers have been underwater for ages and she would have been hammered on the inexperience charge for failing to finish her term as governor. I do think she could have emerged as the “Not Romney” in the race over Cain and a weakened Perry, but realistically there was no way to beat Mitt once it was a binary choice. His campaign pockets are too deep and undecided Republicans are too desperate to beat The One to roll the dice on a nominee who’s arguably unelectable. Once Christie decided not to get in and split the centrist vote with Romney, there was no obvious path for her (which may explain the timing of her announcement today). Worse, there was a chance that she wouldn’t even emerge as the “Not Romney”: If Perry or Cain ended up faring better than her in Iowa or South Carolina, it would have shattered her mystique as the ultimate champion of grassroots conservatives. By staying out, her supporters now get to say “she would have won if she ran” without ever having to test their theory and she gets to kinda sorta play kingmaker as people wait to see if she’ll endorse Perry, Cain, or (gasp) Romney. And who knows? Maybe she’ll focus now on challenging Begich for Senate in Alaska in 2014, which would be a huge first step back towards national viability down the road. She’s 47 years old, fully 25 years younger than McCain was when he was nominated three years ago. No rush.

That was written on October 5 of last year when I thought Santorum was destined for two percent in the polls, somewhere back of Bachmann in Iowa. I was totally wrong. The “Not Romney” sentiment among Republicans was much stronger than I expected, notwithstanding Mitt’s organizational advantages. Had Santorum been able to build just a little on his base of blue-collar and evangelical voters, he might have pulled off a gamechanger in Illinois, Ohio, or Michigan and who knows where we’d be right now. There was in fact a path for a “values”-oriented candidate with a populist touch on economics and questionable electability in the general election. With the benefit of hindsight, Palin — or Huckabee, for that matter — might have taken greater advantage of it than Santorum did. But the point I made back then is still a worthy counterargument to today’s post: If she had run and lost, would it have increased or decreased her stature within the party? If you think it would have declined, then maybe she really did make the right call in passing on the race. It all depends on what odds you would have given her (or Huck) of beating Romney. I think those odds ended up being greater than I initially thought.

Relieved to see that I was consistent about Palin vs. Begich, at least. Whew.