I get a lot of e-mails from readers upset that I am tough on Republican presidential candidates. Many are perturbed that if defective candidates are eliminated they will be “stuck” with Mitt Romney. Rubbish.

Conservatives should be vetting and scrutinizing candidates, assessing their electability and being honest about their shortcomings. Otherwise, they may wind up with four more years of President Obama or a president who is not up to the task. Now is the time to kick the tires and to eliminate fatally flawed candidates. Do conservatives really think the American people haven't noticed that Herman Cain is remarkably ignorant about policy matters, not only for a presidential candidate but for a Republican activist?

As for Romney, Bill Kristol said it best: “Romney may well win as the last man standing,” but there is nothing inevitable about that outcome. If he earns it and wins it, the party will no doubt rally behind him; He is infinitely preferable for conservatives to President Obama. But, as Kristol pointed out:

[E]ven if [Newt] Gingrich fades, let’s not assume it’s over. [Rep. Michele] Bachmann and [Rick] Santorum could still have a run in Iowa. If they continue to trail badly, it’s not out of the question that someone else could still present himself in mid-December to the citizens of Iowa (Hi there, Mike Huckabee! Hello, Sarah Palin!). Or, if Iowa (January 3), New Hampshire (January 10) and South Carolina (January 21) produce fragmented results, and the state of the race is disheartening to Republicans, a late January entry by another candidate isn’t out of the question, either. Couldn’t Jeb Bush or Marco Rubio win the January 31 Florida primary as a write-in candidate in such circumstances?

More to the point, conservatives shouldn’t provide cover for unelectable or unqualified candidates because they think they know where it will lead if they are eliminated. Today there is one poll showing Romney leading Gingrich by only 2 points in New Hampshire, while in Iowa “Massachusetts Gov. Mitt Romney quietly continues to build a loyal, formidable network of supporters in Iowa.” That’s not a result many would have predicted a few weeks ago.

The one thing we know in this primary election is that no one knows much of anything at all. Moreover, once we have a few state contests behind us, voters will begin what one GOP strategist calls the “flight to value.” Voters will see it’s time to pick a winner, rather than their “wouldn’t it be nice” candidate. And as we know which candidates are eliminated early makes a difference in how the electorate is divided up in later states.

So for now it behooves conservatives to play it straight. Cain really does have a knowledge problem. (Rich Lowry dubs it a knowledge-deficit disorder.) Gingrich really does have an electability problem. Let the chips fall where they may, and at the end of the process the least-flawed candidates in the eyes of GOP voters will survive. That’s as it should be.