President Barack Obama’s poll numbers have begun to slide due to increasing pessimism about the economy and his polices’ efficacy, and a subsequent loss of Democratic and independent voter support, a new CBS News poll finds:

President Obama’s approval rating has fallen six points in the past month, a new CBS News poll finds, amid growing skepticism about his handling of the economy and questions about the impact of the stimulus package.

The president’s current approval rating, which is 57 percent, is still relatively high. But it has fallen 11 points from its peak of 68 percent in April, and has also dropped since last month’s mark of 63 percent. His disapproval rating, meanwhile, has risen from 23 percent in April to 32 percent today.

Is this decline due to more Republicans not liking him? Quite the opposite:

The decline in support is coming not from Republicans – whose support for the president has actually risen – but from Democrats and independents. While 82 percent of Democrats still approve of the job Mr. Obama is doing, this number is down ten points from last month.

The president’s support among independents has fallen eight points to 50 percent. Only 30 percent of Republicans back Mr. Obama, though that’s up from 23 percent in June.

The driving issue behind the president’s decline in approval appears to be the economy. His approval rating on handling the economy is now 48 percent, while 44 percent disapprove. Last month, Americans approved of his handling of this issue by a margin of 22 points.

This is a massive drop. Not tiny. Not medium…but a massive polling drop within a short period of time.

The optimism over the economy seen in May – when 32 percent said it was getting better and 23 percent said it was getting worse – has dissipated. Now just 21 percent say the economy is improving, while 33 percent say it is getting worse. Forty-five percent say it is staying the same.

And more:

Half of all Americans expect the recession to go on at least two more years. Fifty-seven percent say the country is on the “wrong track,” up from 50 percent last month. And 44 percent describe the economy as “very bad,” up from 36 percent in June.

Despite White House efforts to stress the implementation of the stimulus package, just 21 percent say it has had a positive impact on the economy. The majority of those surveyed – 60 percent – say it has had no impact, while 15 percent say the stimulus has made the economy worse.

So confidence has been shaken. Some Democrats and Democratic partisans will argue this means he needs to stop fiddling around with foreign trips and get more on message, but being more on message won’t do it. The administration needs to start seeing — and sharing — some real, undisputed good new economic news.

But all is not bleak for Obama & Co.:

Forty-two percent of Americans do say the stimulus will have a positive impact in the long run, however. Twenty-nine percent say it will have no impact, while 21 percent say it will make things worse.

Meanwhile, Gallup’s daily tracking does not quite say the same story. It has Obama’s approval at 59 percent and not quite as drastic a drop.

RealClearPolitics indispensable average of polls doesn’t show Obama in bad shape. It shows his ratings fairly consistent. Here’s its graph:

Pollster.com’s average comes closer to CBS’s, in terms of the actual numbers. But, again, there are signs of slow and steady slippage:

All of this taken together suggests that Obama’s honeymoon is most assuredly over on the economy. These numbers (and some other polls) suggest that most Americans don’t blame Obama for the genesis of this economic crisis, but he now has some of his own key programs in place so if things don’t improve they will blame him — and are blaming him — for programs that are seemingly ineffective or too slow to work.

It also suggests that more than ever the window of opportunity for the Democrats and Obama administration to get policies through a Democratic controlled Congress is closing — particularly because the poll shows that some Democrats are unhappy, which means some Democratic legislators are unlikely to be on the same page as well. Many experts feel the economy could get worse before it gets better. The same could be said for the prospects of the Democrats keeping their majorities, unless the Republicans alienate more Americans (which at times GOPers indeed seem determined to do).