Defenders of Herman Cain proclaim that his sexual harassment scandal hasn’t affected his candidacy. Critics of Michele Bachmann assure us she’s permanently lost her top-tier status. Mitt Romney’s supporters say he’s got a lock on the race, and his critics say he’s incapable of going above 25 percent in the polls.

Don’t believe a word of it. In a sense, everything that came before is a prelude to the next month.

The next presidential debate is scheduled for a week from today, moderated by CNBC’s Maria Bartiromo. There is no shortage of ground to cover, although the topics will most likely be economy-related. Since the last debate, Texas Gov. Rick Perry has rolled out a new economic plan. Cain has introduced complexity to his 9-9-9 plan, so-called opportunity zones that may create new tax rules depending on your zip code. Romney is supposed to give a fiscal reform speech tomorrow. The supercommittee seems destined to fail. And, oh yes, Cain is in the middle of a media firestorm, which his every utterance seems to further inflame.

By the next debate, we’ll be less than 60 days from the Iowa caucus. For many voters, it will be time to get serious about their candidate preferences. A conservative political operative supportive of Romney surmised that only after a few more weeks would public opinion congeal. He told me: “Voters get to that point about 30 days out where they pick a candidate and stick with ‘em, barring a big event. Opinion is a process, so I expect that public polls towards end of November will show a shift to others and away from Cain.” Or they won’t and they’ll decide to vote for him, flaws and all.

An Iowa Republican insider not identified with any campaign contends Cain’s support will melt. He told me: “Given his lack of organization in Iowa, his support was so soft they’re going to be sprinting for the hills and it will absolutely crater. His hard-core supporters remain, but that alone won’t propel him to any measurable success.”

It seems, then, that the next month may be the most volatile month in a very volatile campagin. The Nov. 9 debate and others in the next few weeks may be instrumental in determining the GOP’s central dilemmas: Is there a viable alternative to Romney? And who is best positioned to beat President Obama?

A few weeks ago, Cain had a single problem: Did he know enough to be president? Now he has another: Can he run a campaign, let alone the executive branch? At the CNBC debate, Cain will not only have to defend himself from the underlying allegations of sexual harassment (which may be more detailed by then) but his handling of the matter. He’ll surely run into trouble if he loses his temper, as he did with the media scrum today that wanted some answers. (From my colleague Dana Milbank’s column: “‘What did I say?’ he hissed at the reporters, then attempted to break through the pack, shouting: ‘Excuse me. Excuse me! EXCUSE ME!’ At that, his bodyguards began throwing elbows and shoving the reporters and photographers.”)

Newt Gingrich, Perry, Rick Santorum, Bachmann and others will have their last few opportunities to wean voters away from Cain and to offer themselves as serious alternatives to Romney. A little experience isn’t a bad thing, they’ll argue. The country is a mess, they’ll argue. Do conservatives really want to throw the dice on Cain?

Certainly the candidates better be prepared to answer questions on their own tax plans, on the Greek financial fiasco, on free trade and on entitlement reform. They’ll soon face foreign policy debates where a serious gaffe can be critical. But over the next month, the real question, no matter what the specific topic, will be: Who can go up against Obama, set out a conservative vision and win?

Voters won’t simply reach that judgement by scoring the debate answers. They’ll be assessing the entire person — position, manner, organizational skill, character, experience, knowledge and performance. I would suggest that only as this process unfolds in the weeks leading up to the Iowa caucuses will we see voters make voting decisions, which are different than expressions of preference. The latter are what you tell a pollster, the former is the person with whom you are entrusting the nomination and possibly the presidency.