President George W Bush has said eight more African countries have joined a $1.2bn US programme to fight malaria.
President Bush said defeating malaria was a challenging goal
At a malaria summit in Washington, Mr Bush said 23 countries were now involved in the five-year programme he launched last year.
Malaria is a preventable disease that kills more than a million people every year, 90% of them in Africa, most of them children.
On Wednesday, the World Bank pledged $180m (£92m) to help fight the disease.
The President's Malaria Initiative aims to provide funds to limit the spread of malaria using insecticides and anti-mosquito bed nets, and to provide drugs for people who have been infected.
Parasites that cause malaria are carried from human to human by mosquito
Kills more than a million people a year
90% of malaria deaths are in Africa
Malaria is Africa's leading cause of death for children under five
"The goal of defeating malaria is a challenging goal," Mr Bush told government leaders, officials and malaria activists gathered at the White House.
"We know exactly what it takes to prevent and treat the disease. The only question is whether we have the will to act."
Last year President Bush announced more than $1bn in aid as part of a five-year US initiative to halve malaria-related deaths in 15 African countries which are worst hit by the illness.
The White House summit aims to go further by mobilising the huge charitable resources of the American public, says the BBC's Nick Miles in Washington.
Mr Bush also said he would double US development aid to Africa by 2010.
Other anti-malaria campaigns have failed in the past.
But this time big business including the billionaire philanthropist Bill Gates is getting involved.
This, combined with recent scientific advances - such as progress towards a vaccine - holds out the best hope yet for defeating one of the world's great killers, our correspondent says.
World Bank President Paul Wolfowitz said its new funding - which doubles the bank's previous anti-malaria assistance - needed to be well co-ordinated and monitored to ensure its effectiveness.
Nigerian Health Minister Eyitayo Lambo said malaria was the leading cause of illness and death in the country.