Biden opens up a whopping 16-point national lead over Trump: CNN poll
Joe Biden and Donald Trump (AFP)

Former US vice president Joe Biden has opened up a 16-point national lead over President Donald Trump less than a month before the November 3 presidential election, according to a CNN poll published on Tuesday.

The Democratic presidential candidate leads the Republican incumbent by 57 percent to 41 percent among likely voters, according to the nationwide CNN poll conducted by SSRS.

The survey of 1,001 likely voters was conducted between October 1-4, CNN said -- after the presidential debate and mostly after Trump tested positive for coronavirus.

It has a margin of error of plus or minus 3.6 percentage points.

The 77-year-old Biden handily outpolled the 74-year-old Trump on a number of critical issues, CNN said, including handling of the Covid-19 pandemic, health care, racial inequality and crime and safety.

They were roughly even when it came to who would better handle the economy with 50 percent saying Biden and 48 percent saying Trump.

Fifty-two percent of those polled said they have a positive impression of Biden while only 39 percent said they have a positive view of Trump.

While Biden may lead nationally, the election will come down to which candidate wins several battleground states. Biden has a narrow lead over Trump in most of the key battleground states.

CNN said Biden has increased his lead among women -- to 66 percent to 32 percent -- and also made gains among younger voters, moderates and independents.

The debate appears to have helped Biden with 57 percent of those who watched the clash saying the former vice president did the best job and only 26 percent saying it was Trump.

Hogan Gidley, the press secretary for the Trump reelection campaign, dismissed the CNN poll.

"The same pollsters had the president down and out in 2016," Gidley said on Fox News. "He won the race then and is doing the same thing right now.

"He has great numbers via our internal polling to retain the White House," he said.

An NBC News-Wall Street Journal poll released on Sunday before Trump tested positive for Covid-19 had Biden with a 14-point lead among registered voters.

A RealClearPolitics average of national polls has Biden with a 9.2 point lead over Trump.