Florida, Michigan, Pennsylvania and Wisconsin were critical to President Donald Trump's 2016 win over former Secretary of State Hillary Clinton.
Ahead of this year's election, he is trailing former Vice President Joe Biden, the presumptive Democratic presidential nominee, in all four of them, according to recent polling.
If Trump were to lose those four states on Nov. 3 it would virtually assure a Biden victory.
A Quinnipiac University poll released Wednesday found 46% of registered Florida voters said they would vote for Biden and 42% would vote for Trump.
Voters in Florida disapproved of Trump's handling of the coronavirus outbreak, 51%-46%. But 89% of Republicans approved of the president's response, compared with 87% of Democrats who disapproved. Among independents, 57% disapproved of Trump's response to the pandemic and 41% approved.
Gov. Ron DeSantis was one of the last governors to issue a stay-home-order in response to the outbreak before he did effective April 3. That order is set to expire at the end of the month, but 72% said the state should not loosen the restrictions at the end of the month and 76% said it should only reopen if public health officials deem it safe.
When asked whom they relied on most for accurate information about the outbreak, 62% said health officials, 18% said Trump and 8% said DeSantis.
The Quinnipiac poll was conducted from April 16-20 with a margin of error of plus or minus 2.6 percentage points.
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A Fox News poll released Wednesday found Biden ahead of Trump among registered voters in Michigan, 49%-41%.
That poll also found that Gov. Gretchen Whitmer, whom Biden is considering as a running mate, led Vice President Mike Pence 49%-43% in a hypothetical VP matchup.
Whitmer's 58% favorability rating in the state was higher than Biden's (53%), as well as Trump's (44%). And at 37%, her unfavorability rating was also better than that for Biden (43%) and Trump (52%).
Trump has publicly criticized Whitmer's stay-at-home order in response to the coronavirus outbreak as being too tough and in a tweet last week he declared, "LIBERATE MICHIGAN!"
But 57% of voters there said the restrictions were "about right" and another 9% thought they weren't tough enough. A third agreed with the president that they were "too restrictive."
And 64% said they approved of Whitmer's handling of the crisis, compared to 45% who said the same of Trump.
An Ipsos Public Opinion poll conducted April 15-20 for Reuters also found Biden ahead of Trump in Michigan, 46%-38%.
Another Fox News poll found that 50% of registered voters in the Keystone State back Biden and 42% favor Trump. When asked their opinion of the candidates, Biden fared better than the president with 52% saying it was favorable and 43% unfavorable. For Trump, it was 44% favorable and 53% unfavorable.
Fitty-one percent of the voters in the state disapproved of Trump's handling of the coronavirus response and 44% approved. And 58% thought the president was too slow to respond to the crisis, while 39% thought he acted with "appropriate speed."
By comparison, 69% approved of Gov. Tom Wolf's response to the outbreak. Sixty-two percent agreed with Wolf's stay-at-home order, while 23% thought it went too far and 12% didn't think it went far enough.
Both the Pennsylvania and Michigan Fox News polls were conducted April 18-21 with a margin of error of plus or minus 3.5 percentage points.
The Ipsos/Reuters poll found Biden ahead of Trump in Pennsylvania, 46%-40%.
Biden held a narrow 43%-40% lead over Trump in Wisconsin, according to the Ipsos/Reuters poll, which had a margin of error of plus or minus 5 percentage points.
That poll found Trump's job approval rating in the state at 47%, with 53% saying they disapproved of the president's job performance.
A plan to help the nation recover from the impact of the coronavirus pandemic was rated as the most important factor in choosing the next president by 45% of Wisconsin voters. And 49% thought Trump would be the better man for that job compared with 45% who thought Biden would be better at handling it.
Despite the pandemic, Wisconsin moved forward with its primary election earlier this month. Ten percent of registered voters said they had voted on April 7 and were concerned about being exposed to the virus while 59% who voted said they weren't worried. Another 17% said they didn't vote because of their concerns about infection and 12% said they never planned to vote anyway.
This article originally appeared on USA TODAY: Joe Biden leads Donald Trump in four key states, polls find