It’s not sufficient for a presidential candidate as Obama has demonstrated, but it is necessary for victory.

Here’s Nate Silver’s take on why Newt is likely to be the last “anti-Romney” (I don’t like that term, I prefer “not-Romney” because one doesn’t need to be against Romney to be a viable alternative):

And so here we come to Mr. Gingrich, whose chief attribute all these years — aside from a formidable intellect and a ruthless need to anticipate public opinion — has been the will to endure. He could have shriveled up and left town after his speakership imploded in 1998. Instead, he moved over K Street and ultimately reinvented himself as a political entrepreneur.

He could have quit, as Mr. Pawlenty did, when his campaign hobbled pathetically out of the gate, when his longtime aides quit en masse and the money dried up and he was sleeping in guest rooms because it sure beat the rental car. He probably should have quit, really.

But it turns out that what Mr. Gingrich lacks in glamour or novelty, he makes up for in his sheer imperviousness to humiliation. He didn’t mind getting in the race when even some of his friends thought it self-indulgent. He didn’t mind staying in when the polls showed him barely existing and the commentators mocked him or — worse yet — forgot him altogether. Prudence isn’t his thing.

And don’t kid yourself: in a lot of the candidates whom we later come to think of as gifted and innately credible, this is the characteristic that gets overlooked….

That’s not to say that Mr. Gingrich is following anything like the same trajectory as a Clinton or a Nixon; his campaign still feels more like a protest than a cause. But he has that same unhealthy, irrational need to hurl himself higher onto the slopes of history, no matter what good sense would dictate, no matter what the damage to reputation or privacy.

Determination and personal demons are worth more than you might think in presidential politics. We’re about to find out how much.

With Newt now statistically even with Obama (i.e., slightly ahead) in the latest Rasmussen national poll, and doing well in a variety of state polls, that slope of history is coming into view.