NEW YORK. Oct 20: Bouyed by the endorsement of former US Secretary of State and a four star general Colin Powell, Democratic presidential nominee Barack Obama continues to hold a wide lead over his Republican rival John McCain.

His lead has gone up to 52 per cent than that of 42 per cent for Mr McCain.

More good news for Obama; in one poll, likely voters overwhelmingly rejected John McCain’s effort to make an issue of his association with 1960s radical William Ayers. Fallout also continues from McCain’s pick of Sarah Palin for vice-president, with 52 per cent saying it weakens their confidence in his judgment. And on optimism, it’s Obama by 2-1.

Optimism, meanwhile, is a strong point of differentiation between the two candidates. Likely voters by 62 per cent to 30 per cent see Obama as more optimistic than McCain all else equal, an attractive quality in a candidate, as Ronald Reagan demonstrated. And in a similar attribute, voters by a 17-point margin, 54-37 per cent, see Obama has having the better personality and temperament for office.

On all these, the views of swing-voting independents are critical. They see Obama as more optimistic by 57-31 per cent and as better-suited temperamentally by 52-36 per cent. The Palin pick makes them less rather than more confident in McCain’s judgment by 51-39 per cent, while the Biden selection makes them more rather than less confident in Obama by 50-33 per cent.

Scepticism about the Ayers issue was one of the factors cited by Colin Powell in his endorsement of Obama on Sunday, and in the latest ABC News/Washington Post poll, likely voters broadly agree: 60 per cent say Obama’s relationship with Ayers is not a legitimate issue in the presidential campaign; 37 pe rcent say it is.

There’s less of a split, though, on the Obama campaign’s association with the community group ACORN; 49 per cent say it’s not a legitimate issue, 40 per cent say it is, with more, 11 per cent, unready to express an opinion on the subject. McCain has accused ACORN of voter registration fraud; the group blames some of its canvassers for filling out faked forms, and says it itself has notified the authorities of such cases.

The ABC news poll says that on the vice-presidential candidates, 52 per cent of likely voters say McCain’s pick of Palin has made them less confident in the kind of decisions he’d make as president; that’s up 13 points since just after the selection, as doubts about Palin’s qualifications (also voiced by Powell on Sunday) have grown. Just 38 per cent say it makes them more confident in McCain’s judgment, down 12 points.

Those numbers are more than reversed on Obama’s pick of Joe Biden: 56 per cent of likely voters say it makes them more confident in Obama’s decision-making, 31 per cent less so.

There are other differences among groups. Views of the Palin selection, naturally, are highly partisan. But majorities of moderates (62 per cent), young adults (59 per cent) and women (56 per cent) say it makes them less confident in McCain’s judgment. (More women than men say so.) So do near majorities, 48 per cent, of white women and married women alike.

However, Ms Palin’s pick plays better in the GOP base: 70 of Republicans, 68 per cent of evangelical white Protestants and 67 per cent of conservatives say the selection of Palin makes them more confident in McCain’s decision-making.