WASHINGTON — Every Tuesday, Leslie Pascaud of Shelter Island gathers with friends for a virtual letter-writing session — to chat and catch up as they write postcards to voters in Pennsylvania.

This week, the longtime marketing-executive-turned-Democratic-activist will take a break to watch the first presidential debate between Democratic Vice President Kamala Harris and Republican former President Donald Trump. The 9 p.m. broadcast will come from The National Constitution Center in Philadelphia.

With the presidential election likely to come down to a handful of battlegrounds, attention in New York is heavily focused on the neighboring state of Pennsylvania.

Pascuad is part of a network of New York-based Democratic volunteers who are sending handwritten postcards to voters, making calls to rosters of registered voters and driving on weekends to knock on doors to encourage would-be voters to show up to the polls.

“I can sit in my house surrounded by trees, and probably have a pretty good life, but it’s not the way I see the world,” Pascaud said of her volunteer efforts. “I think other people matter. I think that when you wake up in the morning, if you are only worrying about yourself and those immediately around you, and not connecting to the broader tapestry of this country, you’re missing a trick.”

The long-distance volunteer efforts underscore the all-out fight for votes in a state that Trump won in 2016 by a slim margin of 0.7% and President Joe Biden won in 2020 by a margin of 1.2%. Polls show a statistical dead heat between Trump and Harris. A CNN poll released Wednesday found both at 47% support.

With 19 Electoral College votes up for grabs, political analysts say the state is critical for either candidate’s path to securing the 270 Electoral College votes necessary to win the race.

Over the past week, both campaigns have spent considerable time on the ground — Harris and Biden held their first joint campaign appearance at a Pittsburgh rally on Labor Day, and Harris has remained in Pittsburgh preparing for the debate as running mate Tim Walz and Second Gentleman Doug Emhoff barnstormed the state.

Trump on Wednesday held a televised interview in Harrisburg with Fox News host Sean Hannity, which came on the heels of a campaign rally headlined by running mate JD Vance in Erie.

“You see both candidates investing a great deal in Pennsylvania,” said Daniel Mallinson, a professor of public policy at Penn State University.

For Harris, a win in Pennsylvania would shore up the “blue wall” of states — alongside Wisconsin and Michigan — that Biden flipped in 2020, Mallinson said. While Harris has other paths to an electoral victory that do not include Pennsylvania, the state is shaping up to be a must-win for Trump, as Harris gains ground in Sun Belt states that Biden was trailing before he withdrew from the race in July, Mallinson said.

“The suburbs is where a lot of the battle will probably be in terms of trying to attract voters that might be undecided or might be willing to swing,” Mallinson told Newsday in a phone interview.

Suburban voters were critical to Biden’s Pennsylvania victory, and both campaigns are looking to drum up turnout there, said Susan Liebell, a political-science professor at St. Joseph’s University in Philadelphia.

“Like in New York State, the major cities in Pennsylvania lean more Democratic and rural areas are largely Republican. But also like New York, the population is concentrated in the cities,” Liebell said. “If you look at a map of Pennsylvania, it seems the entire state is red, but the red in the middle is largely rural voters. The suburbs surrounding Philadelphia have a large population, and these are the voters that both parties are looking to capture.”

To woo suburban voters, groups like Swing Left, a national political group formed after Trump’s 2016 victory, have been organizing volunteer efforts like those Pascaud is a part of, connecting volunteers with campaign field offices in swing states and in battleground congressional districts.

Matt Caffrey, senior organizing director for Swing Left, said New York volunteers have played a key part in the organization’s work in Pennsylvania, crediting grassroots volunteers with helping Democrats flip a Pittsburgh-area House seat in 2018 and pick up a U.S. Senate seat with the 2022 victory of John Fetterman.

“The fact that New York is so close, within driving distance to multiple competitive [U.S. House] seats, and multiple population centers, it makes a huge difference,” Caffrey said.

Since April, Hope Singsen, a New York City-based artist and volunteer coordinator with Swing Left, has been organizing weekend carpool caravans from New York to Pennsylvania that are filled with volunteers from the city, Long Island and the Hudson Valley.

“Pennsylvania is the state that we’re hearing the most about as having the power to decide who wins the White House,” Singsen said. “If we can block Trump from winning Pennsylvania, he really may not have a path to the White House. If Trump does prevail and takes Pennsylvania, Kamala still has some other paths, but it’s harder. So, it’s not the whole game, but it still is really, really crucial to win Pennsylvania.”

Republicans also have been working to boost Trump’s support in the state, including encouraging campaign volunteers in New Hampshire to redirect their efforts to Pennsylvania, according to a recent Boston Globe report.

Highlighting the state’s importance in the eyes of both campaigns, an analysis by the firm AdImpact found that Pennsylvania tops the list of ad spending among seven battleground states. The campaigns and aligned political action committees are expected to spend $211 million in advertising there, according to AdImpact — with Democrats expected to spend $109 million in advertising and Republicans expected to spend $102 million in the state. The amount is more than double the $99 million both campaigns are expected to spend in Michigan.

The ad spending has been noticeable, Mallinson said, noting that both campaigns have been blitzing TV and radio with ads.

“A big part of the campaign in Pennsylvania is going to be turning out the faithful,” Mallinson said. “We’ve elected Republican senators, Republican governors, just as we have Democratic senators and Democratic governors. The state clearly can swing.”