WASHINGTON (BLOOMBERG) - Joe Biden leads President Donald Trump by 9 percentage points on the eve of the Democratic National Convention, according to an NBC News/Wall Street Journal poll released on Sunday (Aug 16).

The former vice-president's lead was 50 per cent to 41 per cent, down slightly from an 11-point gap in the same poll series in July.

In 11 combined battleground states - Arizona, Colorado, Florida, Maine, Michigan, Minnesota, Nevada, New Hampshire, North Carolina, Pennsylvania and Wisconsin - Mr Biden was up 7 points, 49 per cent to 42 per cent.

The former vice-president leads Mr Trump on most major issues, including on who would better handle the coronavirus, while the president maintains a double-digit lead on handling the economy.

A majority of potential Biden voters, 58 per cent, say their support is based more on their feelings against Mr Trump. By contrast, 74 per cent of Trump voters cite their support for the president.

The NBC/WSJ poll was conducted from Aug 9 to 12 among 900 registered voters, and had a margin of error of plus or minus 3.3 percentage points.

Separately, an ABC News/Washington Post survey showed that 54 per cent of voters approve of Mr Biden's election of Senator Kamala Harris as his running mate, including 86 per cent of Democrats, 25 per cent of Republicans and 52 per cent of independents.

The RealClearPolitics average of general election polls, which includes the latest NBC/WSJ survey, shows Mr Biden up by 7.9 points.