Democratic Party presidential candidate Joe Biden further boosted his lead over president Donald Trump after two scandals that saw Trump knowingly mislead Americans about the dangers of COVID-19, and condemn Americans that died in combat in World War 1.

A new Yahoo News/YouGov poll conducted Sept. 9 to 11 shows Biden increasing his lead over Trump to 10 percentage points as to who registered voters want as the next U.S. president. Biden upped his lead to 49 percent against 39 percent for Trump.

The previous Yahoo News/YouGov poll saw Biden ahead by just six percentage points immediately after the Republican National Convention, which ended August 27. 

Doing immense damage to Trump's re-election chances were a story in The Atlantic on September 3 where Trump disparaged Americans, killed, wounded or captured in World War 1 as "losers" and "suckers."

The other was veteran journalist Bob Woodward's audio recordings revealed September 9 where Trump admitted he intentionally downplayed the deadliness of COVID-19 allegedly because he didn't want to panic the American people.

"I wanted to always play it down," said Trump to Woodward in mid-March. "I still like playing it down, because I don't want to create a panic."

Those polled by Yahoo News/YouGov were asked if their opinion of Trump's COVID-19 response changed because of what he told Woodward. Twenty-three percent of respondents said, "Yes." Surprisingly, 15 percent of those that voted for Trump in 2016 said the Woodward tapes changed their mind about Trump's handling of the pandemic.

Trump's condemnation of American soldiers killed, wounded or captured in combat also eroded his support among voters. In answer to the question as to which candidate shows more respect for the military, 50 percent of respondents chose Biden compared to 39 percent selecting Trump. By the same margin, voters said Biden will do a better job leading the military compared to Trump.

Independent voters were also horrified at Trump's remarks. Twenty-three percent of Independents said Trump's disparaging remarks increased their support for Biden. Six percent of those who voted for Trump in 2016 said they'll vote for Biden.

The Yahoo News-YouGov poll said even Trump's "October Surprise" – a COVID-19 vaccine before November 3 – might not be enough to save Trump from defeat. A mere 16 percent of registered voters think a vaccine released before Election Day will be safe. On the other hand, 58 percent believe Trump's vaccine will be unsafe.

Sixty-two percent of respondents said it's a bad idea for Trump to pressure health officials to release a vaccine before the election compared to 17 percent who said otherwise.