By Steve Holland, Andrea Shalal, Trevor Hunnicutt

(Reuters) -Democrat Kamala Harris and Republican Donald Trump hit the campaign trail on Saturday, pressing their case with voters from Georgia to Pennsylvania who are already starting to cast ballots in the U.S. presidential election.

Harris and Trump are essentially tied in the most competitive states and many Americans are voting early by mail or in person, with just 17 days until the Nov. 5 election.

On Saturday, Harris will host a get-out-the-vote event in Detroit, Michigan, for the city’s first day of early voting, alongside Michigan-born rapper Lizzo. 

She then 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. Early voting started in Georgia this week. 

“Donald Trump has proven himself to be increasingly unstable and unfit and he is trying to take us backward,” Harris told reporters in Detroit.

Harris will need strong results in the majority non-white cities of Detroit and Atlanta and their surrounding suburbs to repeat U.S. President Joe Biden’s 2020 wins in Michigan and Georgia.

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. 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 said he had not canceled any events. But an Oct. 22 National Rifle Association of America event in Savannah, Georgia, that he had planned to attend, was canceled, according to organizers. 

“I’m not even tired,” Trump said. 

Trump dismissed Harris’ calls for him to release his health records and said Harris should take a cognitive test.