ATLANTA   -   Kamala Harris turns 60 on Sunday in the final stretch of a knife-edge election battle with 78-year-old Donald Trump, who is now the oldest presidential candidate in US history. Age has been a crucial factor in a campaign that President Joe Biden quit over fears about his capacity, and where Harris has steadily taken aim at Trump’s mental fitness for office. With just over two weeks before Election Day, the Democratic vice president and the Republican billionaire are in a fierce race that polls suggest is effectively tied. The two candidates will on Sunday again be in Pennsylvania, the battleground that is considered a must-win among the seven key states expected to decide the November 5 election. Biden passed the torch to Harris after a disastrous debate against Trump raised concerns in the Democratic Party about his mental sharpness. But Trump’s age has not appeared to be a deal-breaker for voters, as polls show a close battle. “Now he’s ducking debates and canceling interviews because of exhaustion,” Harris told a rally Saturday in Atlanta, mocking his rambling, off-script speeches. “He’s called it the weave. But we here, we will call it nonsense,” she added. Harris had also sought to goad Trump with a report on October 12 that described her “excellent health”, but the ex-president’s campaign noted he too is “in perfect and excellent health to be Commander-in-Chief”. The Republican running for a second go in the White House countered Harris’s accusations with a marathon speech in Pennsylvania on Saturday, a day after saying she “doesn’t have the energy of a rabbit.”

Both candidates are spending their final campaign days in pivotal battleground states, but so are their surrogates.

Tesla and SpaceX boss Elon Musk has personally hit the campaign trail in Pennsylvania, holding a series of events in the must-win state.

Speaking in the southeastern city of Harrisburg, he announced he would start to randomly distribute cash awards -- $1 million each day until the November 5 vote -- to a registered voter in the state who signed his organization’s petition.

Harris deployed surrogates in the form of pop stars Lizzo and Usher to make her case to voters.

Lizzo drew cheers when telling a Detroit rally that America was more than ready for its first woman president, dropping a reference to her own hit song: “It’s about damn time!”

One of Atlanta’s major stars, Usher, told voters there that “I’m counting on you” to get Harris’s “campaign across the finish line” in Georgia.