Washington DC - Kamala Harris and Donald Trump are both campaigning in the battleground state of Pennsylvania Monday as the clock ticks on the presidential election, with the Democrat also targeting male Black voters who are drifting to the Republican.

Just over three weeks before voting day on November 5, Vice President Harris and former President Trump remain neck-and-neck in the polls, with both candidates increasingly believing the election will be won or lost in blue-collar Pennsylvania.

Harris will be holding a rally in Erie, the northernmost county in the state and a bellwether in presidential elections since 2008, while Trump holds a town hall in Oaks on the outskirts of Philadelphia.

It marks the start of a week-long blitz of the three so-called Blue Wall battleground states of Pennsylvania, Michigan, and Wisconsin this week by Harris and her running mate Tim Walz.

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In a rare move, Harris will also sit down for an interview with Fox News on Wednesday – seeking to counter Republican claims that she is avoiding tough media questioning.

Harris on Monday also launched a new economic plan for Black men as polls show she is losing ground among a key demographic that helped Joe Biden beat Trump in 2020.

On Tuesday, Harris will appear at a town hall in Detroit with Charlamagne Tha God, a comedian and radio host whose show is popular with young, Black male voters.

Trump will meanwhile be attacking Harris over her previous comments saying she would ban fracking, a controversial method of unlocking underground gas and oil deposits that has brought economic benefits to Pennsylvania.

Harris has since disavowed her earlier comments and says she would not ban fracking as president.

The Harris campaign's moves this week reflect fraying Democratic nerves over polls that have been stubbornly stuck for weeks following an initial burst after she replaced Biden as candidate in July.

A series of polls over the weekend showed Harris marginally ahead or even with Trump in the national vote. However, because of the idiosyncratic electoral college system, a lead of three or more points is often needed for a Democrat to win.

Harris (59) went on the offensive at the weekend, releasing her medical records and challenging Trump – who is at 78 the oldest presidential nominee in US history – to do the same.

Trump responded on X on Monday, saying it was "very important that Kamala Harris pass a test on Cognitive Stamina and Agility," calling her "slow and lethargic in answering even the easiest of questions."

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Trump's speeches have become darker and more rambling in recent months, with the Republican notably demonizing migrants in a misleading address about crime on Friday as he seeks to put the issue at the heart of the election.

Harris and Trump, meanwhile, also remain more or less even in the seven battleground states where the election is likely to be decided – Arizona, Georgia, Michigan, Nevada, North Carolina, Pennsylvania, and Wisconsin.

This week, Harris's focus is on the former Rust Belt states of Michigan, Pennsylvania, and Wisconsin – known as the Blue Wall because they once reliably voted for Democrats, whose signature color is blue.

But Trump broke through to win the three states in 2016 before Biden took them back in 2020.

A Harris campaign official said that she and Walz, a former football coach, were "leaving it all on the field – blanketing the battlegrounds with an aggressive campaign schedule primarily across the Blue Wall this week."

Harris campaigns twice in Pennsylvania, twice in Michigan, and once in Wisconsin, it said. Biden himself is set to attend a political event in Philadelphia on Tuesday as he, too, seeks to boost Harris.

Former President Barack Obama will campaign in Arizona and Nevada this week in a bid to shore up support from Latino voters. Obama caused a stir last week when he chided Black male voters for being reluctant to support Harris.