Just how badly has Barack Obama’s standing dropped this year?  Even killing Osama bin Laden hasn’t kept his re-elect numbers from declining significantly.  Pew’s latest survey shows Obama only one point ahead of a generic Republican candidate, a statistical tie, but his 41% score is even worse news:

The sizeable lead Barack Obama held over a generic Republican opponent in polls conducted earlier this year has vanished as his support among independent voters has fallen off. Currently, 41% of registered voters say they would like to see Barack Obama reelected, while 40% say they would prefer to see a Republican candidate win in 2012. In May, Obama held an 11-point lead.

What happened?  Obama has lost independents, Pew says, and he lost a lot of them in a hurry:

This shift is driven by a steep drop-off in support for Obama among independents. The latest national survey by the Pew Research Center for the People & the Press, conducted July 20-24 among 1,501 adults and 1,205 registered voters finds that just 31% of independent voters want to see Obama reelected, down from 42% in May and 40% in March. Where Obama held a slim 7-point edge among independent registered voters two months ago, a generic Republican holds an 8-point edge today.

This is consistent with a drop in Obama’s approval among all independents. Currently, a majority (54%) disapprove of Obama’s performance for the first time in his presidency. His approval among independents has slipped to 36% from 42% last month and 49% in late May.

The May survey was taken in the final week of the month, obviously while Obama enjoyed some of his post-OBL bump.  In that survey, independents favored Obama over the generic Republican 42/35.  That’s a swing of 15 points in the gap.  He had a 49/37 approval rating among independents eight weeks ago, and the 36/54 in today’s poll is a staggering 26-point change in the gap.

All that’s left is to find Generic Republican and nominate him or her for the 2012 election. Failing that, Pew polls on the announced and potential candidates for the nomination, and don’t find much change in their status.  Romney still leads the pack (21%) with a nine-point lead over second-place finisher Rick Perry (12%), who barely edges out Sarah Palin and Michele Bachmann at 11% each.  Perry ties Romney for the lead at 16% among Tea Party supporters, though, with Bachmann in third at 14% and Palin fourth at 12%.  Romney cruises to a lead among non-Tea Party voters with 25% to Palin’s 10%, and three others finishing at 8%.  But 25% of all non-Tea Party voters have yet to make up their minds, too, as do 20% of all voters.

The erosion of independents is a big problem for Obama.  He needs a big economic recovery to get them back in the fold, or failing that, a way to make Republicans look as bad as possible so that they don’t choose the alternative.  The depth of the fall from May’s surge is remarkable, and looks less reversible than the post-OBL bump proved to be.