Barack Obama, the presumptive Democratic presidential nominee, has taken a convincing double-digit lead over his Republican rival John McCain among registered voters across the US, according to a second opinion poll in four days.A new Los Angeles Times/Bloomberg poll shows that Obama holds a 12-point lead over McCain in a head-to-head match up, 49 per cent to 37 per cent. But when third party candidates Ralph Nader and Bob Barr are added to the list, Obama’s lead over McCain extends to 15 points, 48 per cent to 33 per cent.The survey is the second in a matter of days to indicate McCain, 71, may face a sizable deficit as the general election campaign kicks off. A Newsweek poll released four days ago showed the 47-year-old Illinois Senator with a 15-point lead.According to a CNN analysis of five recent national surveys, Obama holds an 8-point lead over his presidential rival.CNN Polling Director Keating Holland says a substantial lead in June does not always lead to a decisive victory the following November when US goes to poll.“Historically speaking, when June polls show a tight race, the race usually remains tight all the way through November. But when June polls have shown a big lead for one candidate, that lead has often melted,” Holland said.“Bill Clinton was leading Bob Dole by up to 19 points in June, 1996; Clinton won by eight. Michael Dukakis had a 14-point lead over George Bush the elder in June, 1988; Bush won by seven. Jimmy Carter was up nearly 20 points in June, 1976 but in November eked out a two-point win. And Richard Nixon managed an even smaller victory in 1968 even though he had a 16-point margin that June,” Holland noted.
