Harris' campaign declined to comment, but reporters travelling with the campaign were escorted into the headquarters of NBC on Saturday, the network that airs the popular comedy show, and two sources said she would participate. The show airs at 11:30pm (2:30pm on Sunday AEDT).
A Saturday Night Live appearance would add a surprise jolt ahead of the presidential election on Tuesday.
Trump hosted the show in 2015, during his first presidential bid, and in 2004. Other presidential candidates, including Democrat Barack Obama, have also appeared on the long-running show.
Kamala Harris is expected to surprise viewers with a Saturday Night Live appearance. (AP PHOTO)
Earlier on Saturday, Harris and Trump's planes shared the tarmac in Charlotte, North Carolina.
The close encounter was a dramatic illustration of how the two candidates are focusing on a handful of states where Tuesday's US presidential election will ultimately be won or lost.
It was the fourth day in a row that the candidates campaigned in the same state.
Only seven states, including North Carolina, are seen as truly competitive but a Des Moines Register poll released on Saturday showed Harris holding a surprise lead in Iowa, a state Trump won easily in the last two elections.
Harris campaigned in Charlotte, North Carolina, with rock star Bon Jovi, while Trump held a rally in suburban Gastonia. It was not clear whether he was on his plane when Harris arrived.
Trump and Harris stuck to familiar themes at their appearances.
Trump said he would deport millions of immigrants if elected and warned that if Harris wins, "Every town in America would be turned into a squalid, dangerous refugee camp."
Campaigning in Atlanta, Harris said Trump would abuse his power if he returns to the White House.
"This is someone who is increasingly unstable, obsessed with revenge, consumed with grievance, and the man is out for unchecked power," she said.
More than 72 million Americans have already cast ballots, according to the Election Lab at the University of Florida, short of 2020's record early-voting pace during COVID-19, but still indicating a high level of voter enthusiasm.
In North Carolina, the western counties that were devastated by Hurricane Helene appeared to be voting at roughly the same rate as the rest of the state, according to Catawba College political science professor Michael Bitzer.
Trump criticised the federal government's response to the disaster and repeated his false claim that aid had been diverted from the state to help immigrants entering the country.
Donald Trump says he is running for office to save the US economy. (AP PHOTO)
At a later rally in Salem, Virginia, a state that analysts say he is unlikely to win, Trump said he ran for office to rescue the economy from "obliteration", even though it would have been easier to relax at one of his oceanfront resorts.
"I didn't need to be here today," he said.
"I could have been standing on that beach, my beautiful white skin getting nice and being smacked, being smacked in the face by a wave loaded up with salt water."
Trump was joined on stage by women from a local college swim team who have objected to competing against transgender athletes. Some of Trump's TV ads have sought to capitalise on transgender controversies.
Harris and Trump have very different policies on major issues including support for Ukraine and NATO, abortion rights, immigration, taxes, democratic principles and tariffs, which reflect the schisms between the Democratic and Republican parties.
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