A new NBC News poll finds President Obama's job approval at 51%, down 2 points from an NBC/Wall Street Journal poll released last month.

The survey was taken Aug. 15-17 of 805 adults with a +/- 3.5% margin of error.

On health care, the top issue of the month and likely the year, just 41% approve of his handling it and 47% disapprove. Just more than one-third (36%) believe Obama's efforts to reform the health care system is a good idea and a quarter (24%) think health care quality will improve because of it.

Still, 60% think the system needs either a "complete overhaul" or "major reform." Also, 43% are in favor of a public option while 47% oppose it. Respondents were split over whether the protests of health care townhalls this month have done more harm or more good.

More from NBC's Mark Murray:

A plurality believes Obama's health plan would worsen the quality of health care, a result that is virtually unchanged from last month's NBC/Wall Street Journal poll. What's more, only four in 10 approve of the president's handling of the issue, which also is unchanged from July.