(Reuters-Yonhap)

WASHINGTON (AFP) -- A nail-biting US presidential campaign heads into its final week Monday, with polls showing little daylight between the two candidates as they ramp up appeals to their respective bases to turn out and vote.

More than 41 million Americans have already cast early ballots ahead of Election Day on November 5, in what is expected to be one of the tightest elections of modern times.

Outgoing President Joe Biden will join them in casting his own vote Monday, the White House said.

On the campaign trail, both candidates return to key battleground states, with Democrat Kamala Harris heading to Michigan, where she faces opposition from Arab Americans outraged over US support for Israel.

Republican Donald Trump, 78, will head to Georgia, where he will address a gathering of pastors and faith leaders before holding a rally.

The trips come after Harris, 60, spent Sunday going neighborhood to neighborhood in Philadelphia, in must-win Pennsylvania, with stops at a Black church and Puerto Rican restaurant.

"The election is here, and the choice, Philly, is truly in your hands," the Democrat said, in her 14th trip to the state since Biden dropped out of the race in July.

Former president Trump packed a crowd into New York's famed Madison Square Garden arena on Sunday, where -- stoking tensions on immigration -- speakers made crude remarks about Latinos and advisor Stephen Miller declared "America is for Americans, and Americans only."

While Trump accused Harris of having "destroyed the country," his speech was in some ways overshadowed by his openers, including a comedian who called the US territory of Puerto Rico "literally a floating island of garbage."

Firing up the base

Trump and Harris have both pushed hard to bring out their voter bases, with Trump aiming to fire up evangelicals.

As Harris campaigns on abortion rights as central to her message, Trump has taken to extremes to paint her as "radical," falsely claiming she is in favor of "execution after birth."

In Georgia, one of the seven swing states that will decide the election, Trump -- himself not particularly religious -- has enraptured conservative Christian voters, having appointed three Supreme Court justices in his previous term who went on to overturn the national right to abortion.

Harris has warned that Trump "wants to take America back to the 1800s" on the issue as she tries to appeal to women as well as more moderate Republicans.

But the vice president has run into problems with the Democrats' traditionally more multiracial, multifaith base as civilian casualties continue to mount in Israel's war against Hamas in Gaza.

While Harris has at times been more critical of Israel than Biden, her boss, she has also ruled out any major changes in US support for Israel, including an arms embargo.

That could spell trouble in Michigan, another key swing state and home to large numbers of Muslim and Arab American voters who have declared they will not vote for the Democrat.