From candle-lighting to tree-planting, the US president and the Democratic presidential candidate will take part in ceremonies to mark the anniversary of the Oct. 7 attacks on key American ally Israel.

Republican Donald Trump, Harris's rival in a tooth-and-nail election, was also due to take part in events to mark the anniversary of the surprise attacks by Hamas, in which 1,205 people were killed, most of them civilians, and 251 taken hostage.

But with the Middle East on the verge of all-out war and protests planned at home, the commemorations also underscore Biden and Harris's apparent powerlessness to influence Benjamin Netanyahu's conduct of the war.

"Far too many civilians have suffered far too much during this year of conflict," Biden said in a statement.

Biden lashed out at the "unspeakable brutality" of the attacks and said he and Harris were "fully committed" to the security of Israel against Iran and its regional allies Hamas and Lebanon's Hezbollah.

But he also described Oct. 7 as a "dark day for the Palestinian people" and said he and Harris "will not stop working to achieve a ceasefire deal in Gaza."

Harris said she was "devastated by the loss and pain of the Israeli people" but added that she was "heartbroken over the scale of death and destruction in Gaza over the past year."

Both Biden and Harris said in their separate statements that a "diplomatic solution" as Israel pounds Lebanon to tackle the Hezbollah militia was the "only path" to a wider peace.

More than 41,909 Palestinians, a majority of them civilians, have been killed in Israel's military campaign in the Gaza Strip since the war began, according to data provided by the health ministry in Hamas-run Gaza. The United Nations has acknowledged these figures as reliable.

Candle-lighting

Biden and First Lady Jill Biden were set to take part in a Jewish candle-lighting ceremony with a rabbi at the White House at 11:45 a.m. Washington time.

Harris and her husband Doug Emhoff will separately plant a memorial tree at the vice president's residence in Washington, then deliver remarks at 4:00 p.m., said her office.

Former president Trump was due to attend Oct. 7 events in New York and Miami.

Protests against Israel's war in Gaza were expected in New York and several US cities. A man set his arm on fire at a protest outside the White House on Saturday.

The Gaza war has caused political difficulties for Harris and Biden, with Arab and Muslim voters in key swing states and left-wing Democrats strongly opposed to the conflict.

The anniversary meanwhile comes as the Middle East threatens to slide into full-scale war less than a month before the US election, with Israel expected to retaliate imminently for a mass ballistic missile strike by Iran last week.

Biden has urged Israel not to attack Iran's oil facilities, fearing it could push up oil prices, in turn hitting the US economy and harming Harris's election chances.

Over the last year however Netanyahu has repeatedly ignored Biden's calls for restraint.

Senior Democrats have questioned whether Netanyahu is trying to influence the election in favor of fellow right-winger Trump by holding off from any peace deal before the Nov. 5 vote.

Biden said last week that "whether he's [Netanyahu's] trying to influence the election, I don't know" but chided Netanyahu, saying that he "should remember" Washington's strong support for Israel.

Trump has spoken little about the recent escalation in the Middle East in his campaign, although when he does he has blamed Biden and Harris for the crisis.

Last week, Trump said he believes Israel should strike Iran's nuclear facilities, after Biden advised against such an attack.