It’s hard to imagine the conditions that would allow Herman Cain to be the Republican nominee for president. I’m not altogether convinced he even wants the job.

This only makes his new-found lead in national polls that much more striking.

Fueled by Tea Party supporters, conservatives and high-interest GOP primary voters, former Godfather’s Pizza CEO Herman Cain now leads the race for the Republican presidential nomination, according to the latest NBC News/Wall Street Journal poll.

And in yet another sign of how volatile the Republican race has been with less than three months until the first nominating contests, the onetime frontrunner, Texas Gov. Rick Perry, has plummeted to third place, dropping more than 20 percentage points since late August.

“Cain is the leader … That’s the story,” said Democratic pollster Peter D. Hart, who conducted this survey with Republican pollster Bill McInturff.

This isn’t a fluke. This poll comes the same day as a new national survey from Public Policy Polling, which also shows Cain jumping out in front of the Republican pack, taking the top spot and leading Mitt Romney, 30% to 22%. Cain has also nearly passed Romney in this week’s Gallup poll.

In the NBC/WSJ poll, Cain leads the field with 27% support, followed by Romney at 23% and Rick Perry at 16%. The reversal of fortunes from August is amazing — Cain has seen his number soar by 22 points, while Perry’s support has dropped 22 points.

And then there’s Romney, who was at 23% in August and who’s still at 23% now.

I suspect the buzz today in campaign circles will be over Cain taking the national lead, but if we work from the assumption that Cain will not be the GOP nominee — I’d argue, that’s a fairly safe bet — the key takeaway continues to be Romney’s inability thus far to consolidate Republican support, claim the frontrunner spot, and keep it.

Instead, we see a revolving door of non-Romney GOP candidates who generate excitement from party loyalists, at least in part because they’re non-Romney candidates. It’s Cain’s turn, obviously, but it comes after Pawlenty, Bachmann, and Perry had their time in the spotlight. Each saw their support surge than evaporate, but even as their backers moved on, they didn’t move, at least not yet, to the presumptive nominee.

As the Gallup report noted, in nearly every instance since 1959, by this point in the race, the Republican frontrunner enjoyed support of at least 41% before going on to win the party’s nomination. Romney hasn’t even been able to reach 30% in any Gallup poll this year, and in several major polls, the former Massachusetts governor is actually at a lower level now than he was in June.

Jon Chait recently noted, “I don’t see how Republicans could be making this any more plain. They do not want to nominate Mitt Romney.”

I suspect they will anyway, because there’s no one else worthy of the nod. But as we talked about the other day, when was the last time the Republican Party went into a general election with a nominee so much of the party simply didn’t like?

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Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.