There's good news and bad news for Republicans in the most recent round of presidential polling.

The good news is that in Iowa and nationally, the know-nothing reality TV star who has been leading the race for months has finally been toppled as the frontrunner for the GOP nomination. Hallelujah!

The bad news is that Donald Trump has been supplanted by Ben Carson, the one person in the race more ill-informed about politics than Trump.  The retired neurosurgeon now has a double-digit lead among likely Iowa caucus-goers and a four-point lead in the latest CBS/New York Times national poll among likely Republican voters.

Now, maybe that's nothing to worry about. At this point in the 2012 cycle, Herman Cain was having his own little Icarus moment, flying high in the GOP polls before plummeting back to earth. He collapsed, opening the door to Newt Gingrich, but that too proved temporary. In short, things have a way of shaking out as voters get more serious, and eventually order is imposed on the chaos.

Maybe.

Here's what may be different from 2012. All the way through that cycle, Mitt Romney held first or second place in the polling. If he wasn't leading, he was lurking. Four years ago today, for example, Cain had the support of 25 percent of the GOP electorate, but Romney had 24.3 percent, according to the RealClearPolitics polling average.

This time around, according to the RCP average, Jeb Bush is at 7 percent. Marco Rubio is at 9 percent. Combined, the two establishment Republicans with a national profile are pulling barely 15 percent of their party's support, and neither shows any real sign of improving those numbers. Meanwhile, Carson and Trump together account for almost 50 percent of the GOP electorate, a number that is growing not receding. In the past three months, their share of the vote has more than doubled.¹

So what does it mean that almost half of Republican voters claim to support two candidates for president of the United States who lack even a basic grasp of issues, and at times a basic grasp on reality as well? The fashionable explanation in some quarters is, to put it bluntly, those who support Carson and Trump are just dumb.  And while that's a tempting way to dismiss people who disagree with you -- a temptation to which the right and left both succumb too often -- I don't think it suffices. Speaking personally, I have friends and relatives -- good, successful people -- who are ardent members of that 50 percent and far from dumb. ²

They are, however, profoundly alienated from government. They see themselves as mainstream America, and with a little prodding, they have also come to see themselves as marginalized and voiceless. And if mainstream America has become marginalized and voiceless, they are forced to conclude that something has gone seriously wrong with our system of government, so wrong that it can be corrected only by a major shock.

So who cares if Carson has no idea what the debt ceiling is, or if Trump's idea of a Mexican-built wall is silly nonsense? Such details don't matter as long as they get the most important thing right, which is the restoration of mainstream America to its proper prominence. That is the core of the Trump and Carson appeal.

That's also the flaw in their reasoning, at least as I see it:  They are not mainstream America. According to recent polling, 70 percent of Republican voters think they live in a country in which Trump could be elected president. They flat out do not. They live in a country that has twice elected Barack Obama to the White House, and as much as they might like to think otherwise, neither time can be explained away as a fluke.

According to the most recent Gallup numbers, 46 percent of Americans now identify with or lean toward the Democrats, while 41 percent identify or lean toward the Republicans. Subtract out the more moderate Republicans, and you're left with at most 25 percent of Americans who form the conservative base. Viewed from that perspective, they aren't being cheated of their proper voice in national affairs. To the contrary, in a country where a traditional mainstream probably doesn't exist anymore -- a circuitboard may be a better metaphor than a river for modern America -- you could argue that the extraordinary unity, homogeneity and stubborn passion of that 25 percent has given it a voice beyond what its mere numbers would justify.

But of course, they don't see it that way. They don't recognize that while 25 percent is a significant minority in a nation of minorities, it is still nonetheless a minority, and that as such, their long-term interests are better served by compromise than by rejection.

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¹ On July 27, they had a combined 24 percent of the GOP vote, according to the RCP poll average. On Aug. 27, they had 33.8 percent. On Sept. 27, they had 40.4 percent. Today they have 48.4 percent.

² That's in part because here in Georgia, Carson and Trump account for well over 50 percent of the GOP primary vote.