U.S. Democratic presidential frontrunner Hillary Clinton is opening up her lead over her many rivals -- including Republican Rudolph Giuliani, says a U.S. pollster.

"In the most recent poll, she's got 53 per cent support -- a remarkable lead in a multi-candidate field," Gary Langer of ABC News told CTV's Question Period on Sunday.

"She's over 50 per cent for the first time. Barack Obama well back at 20 per cent support -- his lowest of the campaign. She's really had a good few weeks here, and it's showing."

A recent Associated Press analysis found that Clinton is drawing support from women, blacks and voters without a college degree.

She has neutralized the Iraq war issue (she voted for the war) and has taken steps to warm up her brittle public image.

While Clinton would be the first female president, Obama would be the first black one.

His campaign strategy has focused on upscale and black voters, but Clinton holds a lead with the latter and Obama has been losing support amongst black voters.

In addition, the AP analysis found Obama isn't connecting well with voters on an emotional level, doesn't appear to enjoy the grind of retail politics and faces questions about his relative lack of experience.

Langer said Clinton may also be benefiting from fond memories of her husband -- former President Bill Clinton, who served two terms in the 1990s.

"We find that Bill Clinton's legacy is as helpful to Hillary Clinton as Rudolph Giuliani's 9/11 legacy is to him," he said, referring to the Republican frontrunner.

"Two-thirds of Americans approve of how Bill Clinton handled his job as president in retrospect, and six in 10 say they'd be willing and happy to see him back in the White House now as first husband."

However, Americans largely believe she would take the country in a different direction than her spouse, he said.

"So she is helped by her husband's legacy, but not generally pulled back by it, and that is a good position for her to be in."

Clinton vs. Giuliani

If things hold to the nominating conventions of their respective parties late next summer, Americans will be choosing between Clinton and Giuliani as their two main presidential candidates.

Langer noted that much can happen in the coming months to change the dynamic. Some observers say a Clinton loss in the Iowa caucuses -- the first real test for nominees -- could rattle the sense of inevitability her campaign is trying to cultivate.

However, if current trends hold and a vote were held today, Langer said Clinton would prevail.

In January, 49 per cent would have voted for Clinton versus 47 per cent for Giuliani. However, in an ABC News/Washington Post poll released Wednesday, Clinton's lead increased. She would capture 51 per cent support, versus 43 per cent for Giuliani.

Clinton's had a good couple weeks while Giuliani has had a tougher time, Langer said.

Clinton is also benefiting from a gender bounce. Giuliani has a small lead among male voters, but Clinton is very much the favourite of women, he said.

"She even runs evenly in another key group -- married women," he said. In 2004, Bush had an 11-point lead over Democratic challenger John Kerry among that group.

Bush might be part of Giuliani's problem. The current president's popularity is quite low and the Iraq war is very unpopular.

"Bush's approval rating is almost the exact opposite of Bill Clinton's retrospective rating - 33 percent approve, 64 percent disapprove," the poll said.

"More threateningly, as the war in Iraq has grown more unpopular, Bush has presided over a drop in the number of Americans who identify themselves as Republicans - from 31 percent in 2003 to 25 percent on average this year. And Americans by a 20-point margin, 51 percent to 31 percent, say a Democratic president could do more than a Republican to resolve the situation in Iraq."