What a difference a month makes!  Or, rather, what a difference one extraordinary event can make for a very brief time in polling, as well as some ridiculously skewed survey samples.  Five weeks after scoring a +18 in approval in the Washington Post poll from the killing of Osama bin Laden, Barack Obama’s approval rating returned to its pre-OBL mission underwater status — although you’d need to get to the sample data to learn the extent of the fall:

The public opinion boost President Obama received after the killing of Osama bin Laden has dissipated, and Americans’ disapproval of how he is handling the nation’s economy and the deficit has reached new highs, according to a new Washington Post-ABC News poll.

The survey portrays a broadly pessimistic mood in the country this spring as higher gasoline prices, sliding home values and a disappointing employment picture have raised fresh concerns about the pace of the economic recovery.

Obama’s approval rating from the last poll in the series (when the Post partnered with Pew rather than ABC) was 56/38.  Today’s rating is 47/49, almost identical to the mid-April 47/50 Obama received.  The mid-April approval rating was Obama’s worst in the series since the midterm elections, when likely voters gave him a 46/52 approval ratio.  Today’s number represents a drop in the gap of 20 points, a dramatic decline, but it’s more likely just the electorate shrugging off the OBL bump and returning to Obama’s chronically poor performance as President.

And you know who that helps?

New Post-ABC numbers show Obama leading five of six potential Republican presidential rivals tested in the poll. But he is in a dead heat with former Massachusetts governor Mitt Romney, who formally announced his 2012 candidacy last week, making jobs and the economy the central issues in his campaign.

Among all Americans, Obama and Romney are knotted at 47 percent each, and among registered voters, the former governor is numerically ahead, 49 percent to 46 percent.

Actually, it helps pretty much all Republicans.  In another question, the poll surveyed on Obama’s re-election prospects, and once again Obama hit new post-midterm lows.  Only 24% of the overall sample will definitely vote for a second Obama term, while 45% will definitely not do so; among registered voters, those numbers go up to 25/47.  That’s actually worse than last November, when the definite support hit the 24% low mark but Obama only had 41% definitely opposed to a second term.  Against specific Republicans, Obama lost ground to Romney as well as Newt Gingrich and Tim Pawlenty, but in all three cases, the changes were within the margins of error; there were no changes in Obama versus Palin or Bachmann.

On the issues, Obama didn’t move all that much from the post-OBL mission poll — which is not good news for the President:

• Economy – 40/59, was 40/55
• Deficit – 33/61, was 39/58
• Afghanistan – 52/41, was 60/29
• Terrorism – 60/34, was 69/21

Republicans in Congress took the lead on public trust on the economy, 45/42 over Obama, for the first time since December.  The outlook on the economy remains doggedly pessimistic, with only 11% rating it as positive at all, and 89% rating it negatively, the highest since the midterms. Eighty-one percent now rate the economic recovery as “weak,” up from 75% in February 2010.  A large majority, 57/42, do not feel the effects of a recovery on their personal economic situation.  These are not re-elect numbers by any stretch of the imagination.

Finally, let’s look at the sample.  The D/R/I in the April poll sample was a ridiculous 32/22/41.  This sample has a slightly better split, although still skewed at 31/25/39, which still undersamples Republicans.  In a sample more reflective of reality, Obama’s job approval would be lower than the 47% shown here, and he’d be in deeper trouble against Republican challengers than this shows.