WASHINGTON - Americans are growing more pessimistic about the economy and handling it remains President Obama's weak spot and biggest challenge in his bid for a second term, according to a new Associated Press-GfK poll.

And the gloomier outlook extends across party lines, including a steep decline in the share of Democrats who call the economy "good," down from 48 percent in February to just 31 percent now.

Almost two-thirds of Americans - 65 percent - disapprove of Obama's handling of gas prices, up from 58 percent in February. Nearly half, 44 percent, "strongly disapprove." And just 30 percent said they approve, down from 39 percent in February.

These findings come despite a steady decline in gas prices in recent weeks after a surge earlier in the year. The national average for a gallon of gasoline stood at $3.75, down from a 2012 peak of $3.94 on April 1.

U.S. presidents have limited ability to affect gas prices, which are determined in international markets. However, the party out of power always blames whoever is president at the time for high gas prices, as Republican Mitt Romney is doing now and as Democrat Obama did in 2008.

Of all the issues covered by the poll, Obama's ratings on gas prices were his worst.

The public's views tilt negative on his handling of the overall economy; 52 percent disapprove while 46 percent disapprove. In February, Americans were about evenly divided on his handling of the issue.

The economy is the No. 1 issue in the presidential race, thanks to the deepest economic downturn since the Great Depression and one of the shallowest-ever recoveries.

While the recession officially ended in summer 2009, unemployment remains stubbornly high, at 8.1 percent in April. About 12.5 million Americans are out of work.

The increasing skepticism toward the recovery tracks a weakening overall economy as measured by the gross domestic product, and matches economic growth downgrades by many forecasters.

The AP-GfK poll was conducted May 3-7 by GfK Roper Public Affairs and Corporate Communications. It involved landline and cell-phone interviews with 1,004 adults nationwide and has a margin of sampling error of plus or minus 3.9 percentage points.