The road to White House runs through this US state

Both the Harris and Trump campaigns have been pouring enormous resources into Pennsylvania. They are spending more on television advertising there than any other swing state. Both candidates make regular visits.

Harris introduced her running mate pick, Tim Walz, at a rally in Philadelphia. She spent days preparing for her presidential debate in Pittsburgh. She made a tentpole economic speech there two weeks ago.

Last Saturday, Trump held a massive rally in Butler, where in July he was nearly assassinated. On Wednesday he was in Biden’s hometown of Scranton and Reading.

And when the principals aren’t around, both campaigns have other politicians and officials to drum up support.

“A candidate can’t go into a county to talk to 1,200 people,” says former Democratic Pennsylvania Governor Ed Rendell. “The state is too big. There’s just not time. That’s what surrogates are for.”

Rendell notes that the current governor, Democrat Josh Shapiro, is a big help for Democrats here, as he is very popular in the state and a dynamic speaker – qualities that had made him the odds-on favourite to be Harris’s vice-presidential pick.

For Harris, her keys to victory are to post dominating numbers in Philadelphia and Pittsburgh and win the suburbs by enough to offset Trump’s margins in the rest of the state.

An essential part of this strategy is to win over moderate voters and some Republicans – including the more than 160,000 who turned out to vote for former South Carolina Governor Nikki Haley in the state’s Republican primary, held earlier this year, well after Trump had already locked up the party’s nomination.

“What these people need to hear is ways in which both the past record of Kamala Harris and the future plans of Kamala Harris are basically centrist positions – that she is not this crazy, wild-eyed radical leftist,” said Craig Snyder, former Republican Senate staffer who is running Pennsylvania’s “Haley Voters for Harris” effort.

He added that the Harris campaign is making the most extensive effort to reach Republican voters that he’s seen in a generation.

Trump’s strategy is to squeeze all the support he can out of the conservative parts of the state, including by registering and mobilising those who may not have participated in past elections – a move Trump’s campaign officials say is a central focus of their grass-roots effort.

There are signs their work may be paying off, too. Registered Democrats still outnumber Republicans in the state, but the margin is just a few hundred thousand – the smallest its been since the state first began releasing figures in 1998.

While the college-educated voters in the suburbs may be difficult to convince, the Trump team thinks it can also chip away at traditionally Democratic support among blue-collar union voters and young black men.

“We’ve seen nationally that Trump has made some real inroads with African American men,” said Farah Jimenez, a conservative education activist. “They’re here in Philadelphia, and if you can convince them that he speaks more clearly to the things that concern them, it can at least start to provide a base for Republicans in Philadelphia.”