TILTON, United States - Peace activists are urging US voters considering candidates for November's presidential election to instead write "ceasefire" on their ballots in protest over Joe Biden's handling of the Israel-Hamas war.

"Vote Ceasefire" -- a coalition of local anti-war groups -- says the effort allows Americans to give voice to their anger at the Democratic president over the mounting toll of civilian deaths in Gaza as Israel responds to the deadly October 7 Hamas attacks.

Voters in New Hampshire will pick their preferred candidate in either the Democratic or Republican nominating contests on Tuesday but the push is aimed at progressives wishing to put the White House on notice.

"For the last three months, as the world has watched the war in Gaza continue to worsen, the Biden administration has refused all demands to call for a ceasefire and to end US support for Israel," the campaign posted on X, formerly Twitter.

"So we're taking our fight to the place Democrats care about the most -- the polls. While Joe Biden will almost certainly win the Democratic nomination later this year, he must know that the road to get there will be long and hard if he refuses to listen to his constituents."

The October 7 attack resulted in the death of around 1,140 people in Israel, mostly civilians, according to an AFP tally based on the latest official Israeli figures.

In response, Israel has carried out a relentless air, land and sea offensive that has killed at least 25,295 people in Gaza, around 70 percent of them women, children and adolescents, according to the latest toll issued Monday by the health ministry in Hamas-run Gaza.

"Vote Ceasefire" organizers have not indicated what kind of turnout would constitute a success for the campaign and it is unclear how much affect it will have.

Biden himself is not on the ballot and is largely ignoring the contest, after New Hampshire officials clashed with the national party over scheduling.

A separate campaign is urging supporters to write Biden's name on the ballot in exactly the same manner that "Vote Ceasefire" is promoting.

The outcome will not affect the nomination process in any case, as the Democratic National Committee has declared the New Hampshire primary illegitimate.

Biden is expected to win the nomination comfortably.

"I'm doing this as over 80 percent of Democratic voters are in favor of a ceasefire for Gaza and are opposed to the continuing slaughter of civilian men, women and children in Palestine, with the United States-supplied weapons," campaign volunteer and former Democratic state representative Chris Balch said in a video posted to X.

But self-help author Marianne Williamson, who is on the Democratic ballot, said the "Vote Ceasefire" campaign was doing nothing to help the citizens of Gaza.

"A way to actually help create a ceasefire would be to vote for a candidate who has called for one from the very beginning," she posted in response to the campaign's social media statements.