Former Vice President Joe Biden boarded a new campaign plane in Wilmington, Delaware, at 3:18pm as he gets ready to head to Cleveland, Ohio, for the debate tonight.

-ABC News' Molly Nagle

Overwhelming support in Philadelphia and its suburbs lift former Vice President Joe Biden to a clear lead in crucial Pennsylvania, with backing from college-educated white people and women -- notably white, moderate and suburban women -- central to his advantage in a new ABC News/Washington Post poll.

President Donald Trump, for his part, is suffering attrition among his 2016 supporters; 8% of them now back Biden instead. While a small slice of the electorate, it’s a potentially important factor in a state Trump won by 44,292 votes out of nearly 6.2 million cast four years ago.

Likely voters support Biden over Trump by 54 to 45%, almost exactly matching a national ABC/Post poll released Sunday. The result includes more than a 2 to 1 Biden lead in the populous Philadelphia suburbs, home to nearly a quarter of likely voters, and close results in northeastern and western Pennsylvania, leaving only the conservative center of the state clearly to Trump.

See more data on this new poll here.

-Gary Langer of Langer Research Associates, conducted the poll.

-ABC News' Isabella Meneses contributed to this report.

The Biden campaign released Joe Biden and Kamala Harris’ 2019 tax returns, a clear effort to draw a sharp contrast with the revelations about Trump’s tax returns reported by the New York Times, ahead of tonight’s debate.

With Tuesday’s release Biden has made public 22 years of records, and Harris 15 years.

The releases were posted to Biden’s campaign site.

-ABC News' Mary Bruce and Molly Nagle

With unprecedented unemployment in the United States, where health care is inextricably linked to employment, and a coronavirus pandemic ravaging the globe, it's safe to say that on Nov. 3, health is on the ballot.

As it stands, more than 200,000 Americans have died of COVID-19. Another 13 million are unemployed.

Health might be a political football in 2020, but it's also a deeply personal issue that affects every American voter. Given health's crucial significance this year, the nonprofit Commonwealth Fund polled 4,220 likely voters in battleground states between Aug. 25 and Sept. 20 on which health care issues mattered most to them, and which candidate -- President Donald Trump or former Vice President Joe Biden -- they thought would be more likely to address those health concerns.

Here's what the American public said about which health care issues they care about, in advance of the first presidential debate.

-ABC News' Erin Schumaker

President Donald Trump is set to enter the first presidential debate on Tuesday down in the polls, but coming off the high of nominating his third Supreme Court justice. Some top advisers expect a dominant performance by the president, despite the opposing narratives of attacks on Joe Biden's mental state and the Trump campaign's work to raise expectations for the Democrat ahead of the showdown.

With days to go the debate, Trump has carried out conflicting and confounding strategies both repeatedly targeting Biden's mental acuity, claiming at a recent rally he doesn't know he's alive, while also making passing attempts to boost the former vice president as a seasoned debater who could outshine him.

"This guy doesn't have a clue. He doesn't know where the hell he is," Trump told his supporters in Pittsburgh a week to the day before the first debate. "This guy doesn't know he's alive."

At a campaign rally Saturday night in Pennsylvania, the president both attacked Biden as "dumb" before immediately lauding him as an experienced debater. "He’s a dumb guy. Always known as a dumb guy. But we look forward to seeing him in the debate. He's got a lot more experience. He's got 47 years. I’ve got 3 1/2 years. So we'll see. But he's got 47 years of experience."

Biden has brushed off Trump's onslaught of attacks on his mental fitness. "Watch me, Mr. President. Watch me. Look at us both, what we say, what we do, what we control, what we know, what kind of shape we're in," the former vice president said when asked by ABC News about the president's attacks on his cognitive ability.

While some advisers tell ABC News they're nervous as the president enters his first debate since his encounters with Hillary Clinton four years ago -- with Biden having participated in nearly a dozen debates leading up to clinching the Democratic nomination -- others are anticipating a knockout performance by the president and expect the debate to help highlight the former vice president's gaffes, sources familiar said.

-ABC News' Will Steakin, Katherine Faulders and John Santucci