US Vice President Kamala Harris during the election campaign in Las Vegas, Nevada, USA. Photo: Kyodo/VNA

CBS News survey showed that Harris was 4 points ahead of Trump, with 52%-48%. The latest NBC News national polls showed Harris leading Trump 49%-44% within the margin of error.

Analysts say that with the tight race more than one month until the November election, political eyes are fixed on a handful of states such as those serving as presidential battlegrounds, namely Arizona, Georgia, Michigan, Nevada, North Carolina, Pennsylvania and Wisconsin.