Less than two weeks ago, as Obama charmed world leaders and soaked up glowing news coverage like a Bounty paper towel, many were already writing eulogies for John McCain's chances this year. This has become a ritual: Whenever a bunch of polls show Obama with a big lead (like Newsweek's notorious fifteen-pointer), we hear how the favorable political climate, plus the unprecedented enthusiasm for Obama's campaign, make his victory all but a foregone conclusion. So in a way it makes sense that the opposite is true, too: That when Obama slips in the polls, it's thought that there must be some grand defect in his candidacy. Like now, with the Gallup, Rasmussen, and Zogby daily tracking polls in the past couple of days showing McCain either tied with or leading Obama. Until the next swing in the polls, here's why Obama's candidacy is fundamentally flawed.

• David Brooks thinks the reason voters are still "wary and uncertain" is because they "have trouble placing him in his context, understanding the roots and values in which he is ineluctably embedded." Obama has not fully immersed himself in any of the institutions he's been involved in, including the University of Chicago, the Illinois state legislature, and the Trinity Unity Church of Christ. Consequently, it's "hard to plant Obama," and "voters seem to be slow to trust a sojourner they cannot place." [NYT]

• Andrew Sullivan argues that in addition to Brooks's analysis, two other factors account for Obama's inability to break away. The first is the improving conditions in Iraq, and the second is, "paradoxically," Democratic strength in Congress, which has diminished the "threat of the kind of Republican agenda that propelled Bush from 2002 to 2006." [Atlantic]

• Alex Castellanos claims that McCain has kept it close despite the odds because Obama's campaign "presents their candidate as an ever-changing work-in-progress" and "occludes our ability to know this man, depicting him as authentic as a pair of designer jeans." Obama has constantly reinvented himself throughout his life, and he's doing it again in the general election. But "as he moves to fit what he perceives to be a right-of-center country, he distances himself from the simple and authentic passion of a young candidate who once pledged 'Change We Can Believe In.'" [HuffPo]

• The editors of The New Republic write that though the "stars have aligned for Obama, he has yet to take full advantage of what historically has been a great opportunity." That is, in bad economic times, voters should be turning towards the Democrat. But Obama has yet to "articulate a consistent narrative for our economics woes," nor has he been able to "explain the contours of this current crisis...a prerequisite for building faith in his capacity to solve it." [New Republic]

• Mark Penn says the reason Obama isn't leading by ten or fifteen points is because of "the same concerns that the public had about past Democratic presidential nominees Michael Dukakis, Al Gore, and John F. Kerry": that they were weak leaders. [Politico]

• Matt Lewis notes that in the Zogby survey "the most interesting — and telling — thing…is that Obama seems to be losing support among what should be his strongest supporters." This includes young voters, independents, women, and even Democrats. [Town Hall]

• Nate Silver was previously skeptical of the drop shown in national tracking polls, but with a drop in states like Florida and Massachusetts, he thinks Obama now "faces an interesting decision," to either make some big news himself or "let the cycle play out organically, hoping that McCain's negative advertising will begin to backfire on him." [Five Thirty Eight] —Dan Amira

For a complete and regularly updated guide to presidential candidates Barack Obama and John McCain — from First Love to Most Embarrassing Gaffe — read the 2008 Electopedia.