Democratic presidential nominee Hillary Clinton leads her Republican rival by five points and has improved her image over the past month, according to a latest national poll which attributed it to Democrats who have an increased enthusiasm for her.

The former secretary of state has improved her image by as many as nine points after the successful Democratic National Convention in Philadelphia, which concluded on Thursday. "In a head to head just between Clinton and Trump, Clinton hits 50 per cent and leads Trump 50-45. A month ago, Clinton led 45-41 in the full field contest and 48-44 in the head to head so there hasn't been much change.

"But not much change is good news for Clinton," the Public Policy Polling said releasing the results of its latest opinion polls. PPP said the race is shaping up pretty similarly both nationally and at the state level to the margins Barack Obama won by in 2012 - not a huge landslide by any means, but a solid victory.