Scranton, Pennsylvania White House hopeful Donald Trump vowed Wednesday in a speech in the crucial battleground of Pennsylvania to unleash American energy and "drill, baby, drill" as he misrepresented the US' blockbuster record on fossil fuel production.

Wooing blue-collar voters in Scranton, the former coal mining hub where President Joe Biden grew up, the Republican ex-president assailed his Democratic election rival Kamala Harris on US drilling for oil and accused her of forcing the closure of dozens of power stations.

"On day one, I will tell Pennsylvania energy workers to frack, frack, frack, and drill, drill, drill, baby, drill. We're going to frack, frack, frack," Trump said.

"We will have energy independence and energy dominance, as we did just four short years ago. We were energy-independent four years ago. Can you believe now we get our energy from Venezuela?"

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Trump demonized migrants, flung baseless accusations of Democratic election fraud, and misled his audience about his criminal prosecutions and polling, his opponent's policies, US border security, the hurricanes, wind power and much else, too.

But his focus was on the economy – a top issue in the campaign – and he promised to slash household energy bills by 50% as he warned: "If Kamala is re-elected, your costs will go up and your lights will go out."

Under Trump the US exported more crude oil and petroleum products than it imported, but was never close to genuine independence from foreign energy, with imports from Russia in particular spiking.

The country has been smashing records for production of oil, natural gas, and renewable power under Biden, according to data from the Energy Information Administration.

Trump is polling neck-and-neck with Harris in the Keystone State, the once-thriving epicenter of the US industrial heartland, which is considered one of the biggest prizes in the Electoral College system that decides US elections.

Although Biden's family base is in Delaware, he grew up in Scranton and remains enormously popular in the county where it is located, which he won by nine points on the way to claiming the state in 2020.

Harris, Biden's vice president, has maintained a nationwide polling lead of two to three points since mid-August and has been gaining on Trump on the economy, boosted by easing inflation and a robust jobs report last week.

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But the polls in Pennsylvania and the other six swing states likely to decide the election have been much closer.

And with four weeks to go until Election Day on November 5, new Gallup polling shows Trump outperforming Harris 54% to 45% on the economy as he touts proposals for a tariff-led manufacturing "renaissance."

Pennsylvania is seen as a bastion of the working-class vote, and both candidates have visited regularly.

The former president (78) has a second event Wednesday in Reading, 60 miles northwest of Philadelphia.

Trump was last in the Keystone State just four days ago for a defiant return to the site of a campaign rally where he was grazed on the ear by an assassin's bullet in July, joined onstage by billionaire backer Elon Musk.

Harris heads there next week but former president Barack Obama arrives first for a rally on Friday, part of a blitz of key swing states, adding his star power to the Democrat's White House bid in the final month of the campaign.

Harris heads to Nevada later Wednesday for a campaign event in Las Vegas on Thursday. She then hits Arizona, where she will campaign in Phoenix on Friday.