Former vice president Joe Biden leads President Donald Trump in the contested battleground of Pennsylvania, buoyed by strong support in the Philadelphia suburbs and his competitiveness in the state’s western counties that were a Trump stronghold in 2016, according to a Washington Post-ABC News poll.

Biden’s support stands at 54% to Trump’s 45% among the Keystone State’s likely voters and 54% to 44% among its registered voters. Biden’s current edge among likely voters appears sizable but is not definitive, given the five-point margin of error that applies to each candidate’s support. Other polls of Pennsylvania this month have found Biden leading Trump by an average of eight points.

With five weeks until Election Day, the poll finds that 53% of Pennsylvania’s registered voters approve of Trump’s management of the economy, but 57% disapprove of his handling of the coronavirus outbreak, and that issue appears to sway more voters than does the economy. Trump’s overall approval rating in the state among registered voters is 43% positive and 55% negative, with 49% saying they disapprove “strongly.”

Pennsylvania is the most populous of three Rust Belt states that proved decisive in the 2016 election. Trump defeated Hillary Clinton in Pennsylvania as well as Wisconsin and Michigan by less than one percentage point each. All three states had voted for Democratic presidential nominees in the previous six elections before shifting to Trump.

Pennsylvania’s 20 electoral votes make it the most valuable of the three, and the Trump and Biden campaigns have focused their resources accordingly in an effort to tip the state in their candidate’s direction. The candidates, too, have repeatedly campaigned in person in the state, which was home to Biden’s headquarters before the pandemic forced it closed.

The Post-ABC poll suggests Biden is challenging Trump for support among key groups and areas that drove the president’s 2016 win, including White voters without four-year college degrees, who account for about half of Pennsylvania’s electorate. In recent weeks, Biden has pressed the notion that as a Scranton native he has more affinity for blue collar voters than Trump, who was born and raised in wealthy circumstances in New York. Trump has countered that he is their biggest defender.

Trump leads Biden by 17 points among this group in the poll, though Trump won them by more than 30 points both nationally and in Pennsylvania four years ago. Biden also boasts a 23-point lead among White college graduates and a 64-point lead among non-White voters, similar to or larger than Clinton’s advantages with these two groups of voters four years ago.

Trump’s support in Western Pennsylvania also appears weaker than in 2016. Excluding Democratic-leaning Allegheny County, which includes Pittsburgh, Trump has 50% support to Biden’s 47% among registered voters in western counties of the state. In 2016, Trump won these counties by 29 points. In 2012, Republican presidential nominee Mitt Romney won that region by 16 points on his way to losing the state to President Barack Obama.

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Trump has sizable leads in central Pennsylvania, where he won decisively in 2016, and has a smaller edge in northeastern Pennsylvania. In the central part of the state, his lead is nearly 30 points, the same as it was in 2016, while in northeastern Pennsylvania, the president receives 56% support, comparable to four years ago. The Trump campaign has made it a priority to turn out even more voters in these areas than in 2016.

Biden is strongest in Southeastern Pennsylvania. The Post-ABC poll finds the former vice president leading Trump by more than 2 to 1 in the Philadelphia area, including its populous suburbs of Chester, Delaware and Montgomery counties. Clinton won these counties together by a 14-point margin in 2016, and they have grown more Democratic.

Statewide, women voters also are core to Biden’s support, favoring him by 23 points, while Trump holds a narrow seven-point edge among men.

Whatever his current deficit, Trump has a path to holding the state in November if he can replicate what happened four years ago. A month before the 2016 election, several Pennsylvania polls showed Trump trailing by double digits. Clinton’s lead deteriorated in the final two weeks of that campaign, a time in which her campaign was buffeted by renewed questions about her private email system. Exit polls show that Trump won late-deciding voters by double digits and carried the state by about 45,000 votes, or seven-tenths of a percent.

Trump maintains an advantage on enthusiasm, with 71% of registered voters who support him saying they are “very enthusiastic” about doing so, compared with 51% of Biden supporters. A big enthusiasm gap exists between younger and older Biden supporters. Among those ages 65 and older, 79% say they are very enthusiastic about their support. That compares with 27% among voters under the age of 50. Still, 91% of Biden supporters under age 50 rule out voting for Trump.

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Few voters who cast ballots for Trump or Clinton in 2016 are ready to defect, but among those who are there is a slight advantage for Biden. The poll finds that 92% of likely voters who supported Trump four years ago currently support him, but that 8% of them currently support Biden. By contrast, 98% of Clinton voters say they support Biden, with 1% switching to Trump.

One-quarter of Pennsylvania’s registered voters cite the economy as the most important issue in their vote choice — more than any other issue. The coronavirus outbreak is second at 18%, with a trio of issues — crime and safety, equal treatment of racial groups, and health care — grouped closely behind. Ranking lowest is “the next appointment to the U.S. Supreme Court,” with 9% saying it is their top issue.

Trump and Biden supporters view the issues through competing lenses. Among Trump voters, the economy is by far the most important issue, cited by 47%. Crime and safety is next at 22%. Just 3% highlight the coronavirus outbreak. Among Biden supporters, the pandemic is the top issue, cited by 30%, followed by equal treatment of racial groups at 21% and health care at 19%.

About 6 in 10 Pennsylvanian likely voters rate the national economy as not so good or poor, and they split 85% to 15% for Biden. The roughly 4 in 10 who say the economy is good or excellent prefer Trump by a comparable margin, 86% to 14%. Although the president has net positive ratings on his handling of the economy, he has no advantage over Biden on the question of who Pennsylvania voters trust to handle the issue going forward.

Similarly, views of the coronavirus form a dividing line between the candidates. More than 6 in 10 likely voters in Pennsylvania say they are worried that someone in their immediate family might catch the coronavirus while about a third are not worried — and 3% say they or a family member has already caught the virus.

Those worried about the coronavirus support Biden, 75% to 24%, while those who are not worried support Trump by a wider 82% to 16%. In addition to the overall disapproval of the president for his handling of the pandemic, Biden is more trusted to deal with the issue, by 54% to 40% among registered voters.

The poll finds that 54% of registered voters support recent protests against police treatment of Black people, yet voters give differing responses when asked which candidate can better handle aspects of the issue. Biden is trusted by a 20-point margin to handle “equal treatment of racial groups,” but registered voters are roughly divided on which candidate can better handle “crime and safety,” with 50% choosing Biden and 47% choosing Trump.

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On other issues, Biden has a narrow advantage on handling a Supreme Court nomination and healthy leads when it comes to health care and equal treatment of racial groups. The president does not have a significant advantage on any issue.

The survey was mostly completed before the president on Saturday nominated federal appeals court Judge Amy Coney Barrett to fill the vacancy created by the death of Justice Ruth Bader Ginsburg. But a 53% majority of Pennsylvania voters say they would prefer that the winner of the election nominate someone to succeed Ginsburg rather than Trump selecting someone and the Senate going ahead with confirmation proceedings before the outcome of the election is clear. The proceedings are expected to conclude before Election Day.

Similar to national public opinion, more Pennsylvania voters who support Biden say it is “more important” for their candidate to win because of the court vacancy than Trump supporters say about their candidate, 61% to 41%.

Most Pennsylvania voters (65%) say they will cast their ballots on Election Day while slightly more than 3 in 10 plan to vote early, either by mail or in person at an early voting site. Four years ago, 4% of voters in the state cast absentee ballots, but at the time, the state required voters to have an excuse to do so. This year, any Pennsylvania voter can request a mail-in ballot.

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This Washington Post-ABC News poll was conducted by telephone Sept. 15-20, 2020, among a random sample of 808 adults, including 702 registered voters and 567 likely voters in Pennsylvania, with 63% of interviews completed on cellphones and the remainder on landlines. The margin of sampling error for results among registered voters is plus or minus 4.5 percentage points, and the error margin is five points among likely voters.

The Washington Post’s Emily Guskin contributed to this article.