Harris and Trump are essentially tied in the most competitive states and many Americans are already voting early by mail or in person, with just 17 days until the election.
On Saturday, Harris will host a get-out-the-vote event in Detroit, for the city's first day of early voting, alongside Michigan-born rapper Lizzo.
Then, she travels to Atlanta, Georgia, for a rally with pop singer Usher, who is currently headlining a sold-out, three-date concert tour in the southern city.
Democratic presidential nominee Kamala Harris will celebrate her 60th birthday on Sunday. (AP PHOTO)
Early voting started in Georgia this week.
Harris will need a strong result in the majority-non white cities of Detroit and Atlanta and their surrounding suburbs to repeat US President Joe Biden's 2020 wins in those two states.
Trump planned to stage a rally on Saturday in Latrobe, Pennsylvania, seeking to take advantage of what he felt was an improved position for him in opinion polls that show a deadlocked race.
Some voters already have mail-in ballots in the state, which is the biggest prize on election day among battleground states and could tip the 2024 race.
Early voting also starts on Saturday in Nevada, where former President Barack Obama was expected to campaign for Harris in Las Vegas.
Both 2024 candidates spent Friday in closely contested Michigan, trading jabs about their fitness for office.
Republican presidential nominee Donald Trump insists he is not tired from campaigning. (AP PHOTO)
Trump, 78, dismissed accusations from Harris that he was exhausted by the pace of the campaign's closing days.
Harris turns 60 on Sunday.
Trump insisted he had not cancelled any events.
But an October 22 National Rifle Association of America event in Savannah, Georgia, that he had planned to attend was cancelled, according to organisers.
"I'm not even tired," he said.
Trump dismissed Harris' calls for him to release his health records and said Harris should take a cognitive test.
