WASHINGTON - U.S. President Barack Obama's standing in a new Associated Press-GFK poll suggests he could be in jeopardy of losing a re-election bid in November 2012, even as the survey showed that the U.S. public's outlook on the economy appears to be improving.

Obama's re-election prospects are essentially a 50-50 proposition, according to the poll. It found that most Americans say the president deserves to be voted out of office even though they have concerns about the Republican alternatives.

The Republican candidates held their last debate Thursday before the Jan. 3 Iowa caucuses lead off the battle for the nomination to challenge Obama. Former House speaker Newt Gingrich looks to maintain his recent lead while former Massachusetts governor Mitt Romney and other rivals work to tear him down.

The poll found Americans were evenly divided over whether they expect Obama to be re-elected next year.

For the first time, the poll found that a majority of adults, 52 per cent, said Obama should be voted out of office while 43 per cent said he deserves another term. The numbers mark a reversal since last May, when 53 per cent said Obama should be re-elected while 43 per cent said he didn't deserve four more years.

Obama's overall job approval stands at a new low, with 44 per cent approving and 54 per cent disapproving.

Heading into his re-election campaign, the president faces a conflicted public. It does not support his steering of the economy, the most dominant issue for Americans, or his overhaul of health care, one of his signature accomplishments, but it also is grappling with whether to replace him with Romney or Gingrich.

Romney was still campaigning in Iowa on Friday as he looked to halt Gingrich's momentum. He planned a campaign swing through South Carolina later in the day, where he was picking up the endorsement of Gov. Nikki Haley, The Associated Press has learned from a Republican with knowledge of the endorsement. The party member disclosed Haley's decision ahead of the official announcement on condition of anonymity.

Gingrich was returning to Washington after comparing himself to Ronald Reagan in Thursday's debate and insisting that he can defeat Obama in 2012. He added that it was laughable for his rivals to challenge his conservative credentials.

Despite the soft level of support, many are uncertain whether a Republican president would be a better choice. Asked whom they would support next November, 47 per cent of adults favoured Obama and 46 per cent Romney, the former Massachusetts governor.

Against Gingrich, the Republican front runner and former speaker of the House of Representatives, the president holds a solid advantage, receiving 51 per cent compared with 42 per cent.

The Associated Press-GfK Poll was conducted Dec. 8-12 by GfK Roper Public Affairs and Corporate Communications. It involved landline and cellphone interviews with 1,000 adults nationwide and has a margin of sampling error of plus or minus 4 percentage points.

The wild card in the Republican race is Texas Rep. Ron Paul, with the small-government libertarian surpassing Romney in some polls of Iowa voters.

In Thursday's debate, Paul said the U.S. has no legitimate claim to block Tehran from developing a nuclear weapon and he expressed his anti-war, anti-interventionist views so vehemently that he may have turned off mainstream Republicans who otherwise might have helped him to a surprising first-place finish.

"To declare war on 1.2 billion Muslims and say all Muslims are the same, this is dangerous talk," Paul said of the idea of taking pre-emptive action to prevent Iran from developing nuclear weapons. "Yeah, there are some radicals. But they don't come here to kill us because we're free and prosperous ... They want to do us harm because we're bombing them."

Fellow candidate and Rep. Michele Bachmann said, "I have never heard a more dangerous answer for American security."