Presumptive Democratic presidential nominee Barack Obama has opened the election campaign with a six-point lead over Republican John McCain, according to an NBC News/ Wall Street Journalpoll.
The Illinois senator leads McCain among registered voters, 47 to 41 per cent. In a previous NBC/ Journalpoll in late April, Mr Obama was leading the Arizona senator by three points, 46 per cent to 43 per cent.
Among respondents who said they voted for Senator Hillary Clinton in the Democratic primaries, 61 per cent favoured Obama, and 19 per cent said they preferred Mr McCain.
The poll found Mr Obama leading his rival among African Americans, Hispanics, women and blue-collar workers.
Among white men, who made up 36 per cent of the electorate in the 2004 presidential election, the Republican has a 20-point lead over Mr Obama, however - 55 per cent to 35 per cent, NBC reported.
Mr Obama's lead over Mr McCain expands when Hillary Clinton is added as the former's running mate, the survey found.
An Obama-Clinton ticket would defeat a Republican one of McCain and former Massachusetts governor Mitt Romney by nine points, 51 per cent to 42 per cent, NBC said.
It was not all good news for Mr Obama, however. The chief of his search for a vice presidential running mate stepped down from that role yesterday over questions about loans he received from a company involved in the US housing crisis.
Mr Obama said that Jim Johnson had decided to quit the unpaid position to avoid being a distraction from the process of gathering information about possible vice presidential candidates.