United States President George W Bush and Democratic challenger Senator John F Kerry are both neck-and-neck in opinion polls with Bush leading over Kerry on national security issues and leadership in the war on terror, even as voters continued to give Bush negative marks on Iraq and his handling of the economy.

Forty-eight per cent of likely voters questioned in an ABC News-Washington Post survey said they would vote for Bush while 48 per cent opted for Kerry. Two per cent preferred independent candidate Ralph Nader.

The percentages were virtually unchanged from a survey taken immediately after the Democratic convention.

The survey offered conflicting evidence on the impact of the controversy over Kerry's Vietnam record and television ads attacking his character aired by a group called Swift Boat Veterans for Truth.

A solid majority of voters said they believed Kerry deserved the medals he won in Vietnam and most voters see the issue of Vietnam as irrelevant to their choice in November.

But in the past month, Kerry's personal image has deteriorated, with almost as many voters viewing him
unfavourably as favourably.

The polls, however, showed that despite clear dissatisfaction about the direction of the country, Bush had
regained ground lost to Kerry on national security issues.

The new poll found that a slight majority of registered voters -- 53 per cent-- said Bush was more qualified than Kerry to be commander-in-chief, while 43 per cent said they preferred the Democratic nominee.

Bush's ratings have come from eroding perceptions of Kerry and not as a consequence of improved views of Bush's performance as president, the ABC-Post survey claimed.

Bush's job approval rating stands at 50 per cent, where it has largely been for the past six months.

However, Bush faces flak over his handling of the economy with fewer than half of all Americans -- 45 per cent -- approving of the job Bush is doing on the economy.

Fewer than half also approved of the way he was dealing with the situation in Iraq.

Bush scores on the terrorism front with six in 10 giving him high marks for the way he has handled the war on terror, up from opinion polls conducted last month.

Overall, a majority of Americans -- 54 percent -- said they were dissatisfied with the way things are going in the country, unchanged from July and a sign that Bush remains vulnerable despite his ratings.

But when matched against Kerry on issues and character, Bush either has closed the gap or surged ahead on virtually every measure.

Bush was viewed as more honest and trustworthy than Kerry by a 47 per cent to 41 per cent ratio.