The decline in Obama's approval rating on the issue cuts across party lines, with approval falling from 70 percent last summer to 54 percent now among Democrats; from 57 percent down to 32 percent among independents, and from 36 percent to 16 percent among Republicans.

The poll will provide at least one benchmark for how persuasive Obama is in laying out his plan for Afghanistan, something that post-speech polls should reveal.

Obama's overall approval rating, which had dropped below 50 percent for the first time in a previous Gallup poll, has now inched above 50 percent again.

But on seven specific issues, including Afghanistan, approval of his performance is under 50 percent, although his numbers on the other issues show minimal declines compared to previous Gallup polls.

The issues in which he is in positive territory are energy policy, with 49 percent approving and 39 percent disapproving, and global warming, with 44 percent approving and 36 percent disapproving.

On the negative side, 47 percent disapprove of his handling of terrorism while 45 percent approve; 53 percent disapprove of his handling of the economy while 44 percent approve; 53 percent disapprove of his handling of health care policy while 40 percent approve, and 55 percent pan him when it comes to creating jobs while 40 percent approve.