Last month, Newsweek’s poll surprised many by showing a huge gap between Barack Obama and John McCain, with the Democratic nominee-apparent enjoying a 15-point lead over the Republican.  One month later, Obama has lost all of the momentum and has dropped into a virtual tie with McCain.  The latest Newsweek poll shows Obama up 44-41, within the margin of error:

A month after emerging victorious from the bruising Democratic nominating contest, some of Barack Obama‘s glow may be fading. In the latest NEWSWEEK Poll, the Illinois senator leads Republican nominee John McCain by just 3 percentage points, 44 percent to 41 percent. The statistical dead heat is a marked change from last month’s NEWSWEEK Poll, where Obama led McCain by 15 points, 51 percent to 36 percent.

Obama’s rapid drop comes at a strategically challenging moment for the Democratic candidate. Having vanquished Hillary Clinton in early June, Obama quickly went about repositioning himself for a general-election audience–an unpleasant task for any nominee emerging from the pander-heavy primary contests and particularly for a candidate who’d slogged through a vigorous primary challenge in most every contest from January until June. Obama’s reversal on FISA legislation, his support of faith-based initiatives and his decision to opt out of the campaign public-financing system left him open to charges he was a flip-flopper. In the new poll, 53 percent of voters (and 50 percent of former Hillary Clinton supporters) believe that Obama has changed his position on key issues in order to gain political advantage.

More seriously, some Obama supporters worry that the spectacle of their candidate eagerly embracing his old rival, Hillary Clinton, and traveling the country courting big donors at lavish fund-raisers, may have done lasting damage to his image as an arbiter of a new kind of politics. This is a major concern since Obama’s outsider credentials, have, in the past, played a large part in his appeal to moderate, swing voters. In the new poll, McCain leads Obama among independents 41 percent to 34 percent, with 25 percent favoring neither candidate. In June’s NEWSWEEK Poll, Obama bested McCain among independent voters, 48 percent to 36 percent.

The sample probably provides the quickest analysis of why Newsweek got such a wide variance in their polling [see update below].  The June sample had 324 Democrats to only 231 Republicans, and the overall sample size was smaller.  In July, they may have swung a little too far the other way, with  324 Democrats again but 315 Republicans.  The actual difference in registration figures are wider than that, but not nearly as wide as June’s sample.

But there is a definite momentum away from Obama, especially within the independents.  June’s poll, taken only three weeks ago, had Obama ahead by 12 points, 48-36.   Obama has lost a whopping 14 points among independents and now trails McCain, 34-41.  “Undecided/Other” rose among independents from 16% in June to 25% in July, which likely shows flirtation with third-party candidates such as Ralph Nader and Bob Barr — but some went to McCain as well.

The Hillary Clinton supporters didn’t show any real movement at all.  They went 70/17 in the new poll, and in June went 69/18.  Despite Obama’s suggestion that he attracts Republicans in large numbers, the crossover vote is almost identical, just as it was last month.

Newsweek speculates that Obama’s embrace of Hillary has damaged his brand of New Politics.  That did a lot less damage than Barack Obama’s series of policy reversals and gaffes over that three-week period.  He has revealed himself as an empty suit and a pandering rookie, and he certainly didn’t need Hillary to point that out.

Update: A reader points out that the last page of the polling data shows a R/D/I split of 28/35/33, which doesn’t match the raw sample numbers.  The report states that Newsweek weighted the data in accordance with demographic information from the Census Bureau.  If they weighted the sample to this degree, then Obama’s in much bigger trouble than I first thought.