Barack Obama will hold another prime-time press conference tonight, and it’s not difficult to see why.  One poll after another has shown confidence in Obama eroding, especially on the economy and even on health care, the two topics Obama will address in his presser.  The latest polling comes from the Associated Press, and it adds to the growing consensus among pollsters that Obama has slipped badly over the last month:

That was fast. The hope and optimism that washed over the country in the opening months of Barack Obama’s presidency are giving way to harsh realities.

An Associated Press-GfK Poll shows that a majority of Americans are back to thinking that the country is headed in the wrong direction after a fleeting period in which more thought it was on the right track.

Obama still has a solid 55 percent approval rating — better than Bill Clinton and about even with George W. Bush six months into their presidencies — but there are growing doubts about whether he can succeed at some of the biggest items on his to-do list. And there is a growing sense that he is trying to tackle too much too soon.

The number of people who think Obama can improve the economy is down a sobering 19 percentage points from the euphoric days just before his inauguration. Ditto for expectations about creating jobs. Also down significantly: the share of people who think he can reduce the deficit, remove troops from Iraq and improve respect for the U.S. around the world, all slipping 15 points.

On overhauling health care, a signature issue for Obama, hopes for success are down a lesser 6 points.

The questions and calculations can be found here.  The sampling looks a little skewed, although not nearly as much so as the CBS polls.  With leaners, the poll shows a 48-38 split with 14% either independent or unsure.  When the leaners are taken out and added back into the independent column, though, the sample becomes 34% Democrats, 23% Republicans, and 40% independents.  Again, since Obama got a decent-size crossover vote from Republicans in 2008 and by seven points, an eleven-point gap in favor of Democrats looks pretty strange — especially while the polling has turned poorly for Obama and the Democrats.

Even with that, Obama has deep problems with voters on issues that go to the heart of his agenda.  On the economy, Obama blew a 23-point gap in three months, going from 58-35 approval to 50-46, within the margin of error.  His 25-point gap on health care has been reduced to seven points, 50-43, barely hanging onto a majority in an issue that Democrats have owned for years.  Obama still has a health lead on the environment (56-31), but his disapproval has shot up 12 points. On taxes, his approval gap went from +19 to +2, a statistical dead heat.  His 30-point lead on unemployment shrank to nine points.  He’s also under water on immigration (39-41); three months ago, he had an 17-point lead, 47-30.

On the deficit, though, Obama has lost almost all credibility outside his own party.  Three months ago, Obama had an eight-point lead but not an outright majority, 49-41.  He now has a majority disapproving on the deficit, 51-39, a twelve-point dip into the red.  When asked it Obama would likely shrink the federal deficit, respondents overwhelmingly said no, 60-35.   In January, Obama had a plurality who believed he would, 49-45, which makes this a 29-point flip in six months.

People have seen Obama’s economic policies up close for the first time, and they don’t like them.  As Obama tries to push his radical agenda on health care and energy through Capitol Hill, members of Congress will be looking at those numbers and balking more often.  Obama hopes to change the trajectory of the numbers with a prime-time presser and a flood of media appearances this week, but clearly the American electorate has stopped paying attention to the campaign and focused on results — and they’ve found Obama wanting thus far.

Update: The first link was bad; I’ve fixed it.  Thanks to HA reader TR4A, my cousin Mike, for the correction.