Three weeks before election day, the White House race between US president Barack Obama and his Republican foe Mitt Romney remains statistically tied, with Obama maintaining just a slight advantage, a new opinion poll found Monday.

The latest ABC News/Washington Post survey showed that likely voters favoured Obama over Romney by 49 percent to 46 percent, which is within the poll's margin of error.

But Obama was still leading in nine battleground states -- Colorado, Florida, Iowa, Nevada, New Hampshire, North Carolina, Ohio, Virginia and Wisconsin -- by 51-46 percent.

The mood of the voters slightly improved although most of them remained gloomy. According to the survey, only 42 percent of registered voters said the country was headed in the right direction.

The good news for Obama is that that figure was up by 13 percentage points since late August and, experts say, has reached a level at which an incumbent can survive.

Neither candidate has so far managed to sway the voters toward their economic plan, the survey showed.

Just 51 percent of likely voters expressed confidence the economy will improve under Romney, and 48 percent said the same about Obama.

But the Republican nominee has the class factor to worry about. According to the survey, 57 percent of likely voters believed he would do more as president to favour the wealthy than the middle class. Sixty-eight percent thought Obama had favoured the middle class.

The race factor also plays a certain role. Obama trails by 11 points among whites, but has an overwhelming 73-18 percent lead among non-whites, the poll found.

The survey of 1,252 adults, including 1,063 registered voters and 923 likely voters, was conducted October 10-13 and had a margin of sampling error of 3.5 points.