Stu Rothenberg echoes what I (and many others) have said, which is that the presidential race is in large part all about Obama and whether the country will accept him - his experience, his past associations, his policy prescriptions, and to a certain degree his race - or not.

If he can seal the deal with the public, then he's likely to win - and it could be a very substantial victory. If he can't seal the deal, then he may very well lose - and if things really go south and he loses the center badly to McCain, it could be a bigger defeat than most people can fathom at the moment.

Many pundits, especially those on the left, have been confounded by the fact that for all the money, the enthusiasm, and the favorable political dynamics this year, Obama isn't further ahead in the polls. To the contrary, Obama's small but steady lead over McCain is evidence that he remains in a somewhat precarious position, and that some voters remain apprehensive or unsure about his candidacy.

The new NBC News/Wall St. Journal poll highlights the issue well. On one hand, Mr. Obama's core supporters are vastly more enthusiastic than McCain's, by a margin of 44 to 14. On the other hand, voters see Obama as the "riskier" choice by far :

Regardless of who you may be supporting for president...

As you think about the presidential race and the direction in which the next president will take the country, who do you think would be the riskier choice for president - John McCain or Barack Obama?

John McCain 35
Barack Obama 55
Both 3
Neither 1
Not Sure 6

The key for Obama is closing this gap, which is what this week's overseas tour is all about. It'll be interesting to see in the next round of polls, after the news and images from his tour have been fully ingested by the public, if he's made any progress toward easing voters' doubts about the "riskiness" of his candidacy.