Democrat Kamala Harris and Republican Donald Trump head to North Carolina on Saturday to try to clinch support in the southeastern battleground state just three days before Tuesday's US presidential election.

It will be the fourth day in a row that Vice President Harris and former President Trump visit the same state on the same day, underlining the critical importance of the seven states likely to decide the race, which opinion polls show to be on a knife's edge.

More than 70 million Americans have already cast ballots, according to the Election Lab at the University of Florida, below the record early-voting pace in 2020 during COVID-19, but still indicating a high level of voter enthusiasm.

Saturday also marks the last day of early voting in North Carolina, where over 3.8 million votes have been cast, while the state's western reaches are still recovering from Hurricane Helene's deadly flooding.

Harris plans appearances with rock star Jon Bon Jovi in Charlotte, the biggest city in North Carolina, which is tied with Georgia for the second-biggest prize of the swing states. Each has 16 votes in the Electoral College, where 270 are needed to secure the presidency.

North Carolina backed Trump in 2020 but elected a Democratic governor on the same day, giving hope to both parties.

"We have an opportunity in this election to turn the page on a decade of Donald Trump, who has spent full time trying to have the American people point fingers at each other," Harris said at a rally in Janesville, Wisconsin, on Friday.

Trump will hold a rally in Gastonia, west of Charlotte, at noon (1600 GMT) before returning to the state in the evening, where he is due to speak at the 22,000-seat First Horizon Coliseum arena in Greensboro.

"This election is a choice between whether we... have four more years of gross incompetence and failure, or whether we will begin the four greatest years in the history of our country," Trump told a crowd in Michigan on Friday.

Policy differences

Harris and Trump have very different policies on major issues including support for Ukraine and NATO, abortion rights, immigration, taxes, democratic principles and tariffs.

Harris and Trump were both in North Carolina on Wednesday, Nevada on Thursday and Wisconsin on Friday - all battleground states - at one point holding events around 7 miles (11 km) from each other.

It indicates the enormous effort put on persuading a relatively small number of voters in a few states, because the other states are seen as safely Democratic or Republican.

But Trump will also visit Salem, Virginia, on Saturday despite polls showing a clear lead there for Harris.

Harris will also be in the swing state of Georgia on Saturday, where film director Spike Lee and singer Victoria Monet are due to speak at a rally.

President Joe Biden, a Democrat, won Georgia by just 0.3 percentage points in 2020, the first time his party had picked up the state since Bill Clinton in 1992.

Democrats will be heavily reliant on Black voters turning out and backing Harris if they want to recreate Biden's success in a state where Black people make up just over 12% of the population.

Hispanics, who total nearly 19% of Georgia's population, are also being fought over. Trump holds a narrow 1.6 percentage-point lead over Harris in the state, according to the polling average from FiveThirtyEight.

Heading into the final stretch, on Monday the Harris campaign plans to hold simultaneous interconnected organizing events across all seven battleground states to mobilize voters, according to a senior campaign official.