Coupled with a decided lack of enthusiasm by the president's most liberal supporters, this poll from Pew delivers a sharp jab to the president's reelection chances:

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.

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.

Since there are more independents today than there were in 2008, the 15 point swing in support for his reelection among Indies is very significant. He will probably need more of them in 2012 given the probability that many liberals will either stay home or vote for a third party candidate - if one runs against him in the general election.

Of course, there is still time for the president to recapture those independent voters. But to date, Obama has not demonstrated the political acumen to engineer such a comeback. As long as the economy is in the tank, the president will be hard pressed to win in 2012.