Democrat Kamala Harris leads Republican Donald Trump 42% to 37% in the race for the November 5 US presidential election, according to an Ipsos poll published on Thursday, Reuters reports.

The poll found Harris had widened her lead since a July 22-23 Reuters/Ipsos survey, which found her up 37% to 34% over Trump.

The nationwide poll of 2,045 US adults, conducted August 2-7, found 4% of those surveyed backed independent candidate Robert Kennedy Jr., down from 10% in July.

The poll, conducted online, had a margin of error of around 3 percentage points.