For the first time since taking office, US President Barack Obama's job approval rating has dropped below the 60 per cent threshold as Americans expressed doubts about his handling of the economy, the deficit and health care, a new opinion poll showed yesterday.

The ABC News/Washington Post survey showed Mr Obama's job approval rating fell to 59 per cent, down 10 points from its springtime peak.

Slightly more than half of Americans, 52 per cent, now approve of his work on the economy, down eight points from its peak, according to the poll.

Just under half, 49 per cent, approve of his handling of health care, a drop of eight points. And only 43 per cent approve of his handling of the budget deficit, with 49 per cent disapproving, the survey indicated.

Mr Obama has scheduled a prime-time news conference for late tomorrow to address the issues at hand.

The president's falling numbers have offered some hope to Republicans, but the GOP's overall approval ratings remain low, the poll showed.

Approval of the way the Republicans in Congress are handling their job is up six points since spring and up 11 points from a year ago.

However, it still stands at just 36 per cent, with 58 per cent disapproving, according to the survey.

The poll was conducted by telephone between July 15 and 18 among a random national sample of 1,001 and had a 3.5-point margin of error.