President Bush has announced that former presidents Mr Bill Clinton and Mr George Bush snr will spearhead efforts to raise private American money for countries damaged by the Asian tsunami.
"The greatest source of America's generosity is not our government, it's the good heart of the American people," Mr Bush said at a hastily arranged appearance with his Democratic predecessor and his father in the White House on his return to Washington after a week-long holiday in Texas.
Moving apparently to counter criticisms that he was slow to act initially, Mr Bush said: "The devastation in the region defies comprehension and I ask every American to contribute as they are able to do so."
The White House spokesman, Mr Scott McClelland, said Mr Clinton and Mr Bush snr will travel across America to encourage people and businesses to donate to non-governmental international organisations which provide relief and reconstruction.
Mr Bush and the two former presidents later visited the Washington embassies of Indonesia, Sri Lanka, India and Thailand - the four hardest-hit countries - to sign books of condolences.
The recruitment of Mr Clinton fuels speculation in Washington that Mr Bush is planning a significant international role in his second term for his predecessor.
The visit to the embassies also served to emphasise the personal involvement of the president in reacting to a world catastrophe in a heavily Muslim area which the US seeks to engage in the war on terror, and in seizing an opportunity to enhance the international prestige of the US in the region.
The scale of the response of the world superpower in terms of military, government, corporate, NGOs and individuals has grown rapidly in recent days. US naval ships, including an aircraft carrier with a fleet of helicopters, and 12,000 US military personnel, are engaged in getting fresh water and supplies to devastated areas and the 1,000-bed hospital ship Mercy is en route to the Indian Ocean.
The US Secretary of State, Mr Colin Powell, arrived in Bangkok yesterday with the president's brother Mr Jeb Bush, governor of Florida, on the first leg of a tour of affected countries.
Mr Powell said he did not expect to announce an increase in the $350 million in aid pledged by the US government, but in Washington, Democratic senator Mr Joseph Lieberman said that the sum - a third less that that ear-marked by Japan - would be "a floor, not a ceiling".
With about $2 billion now pledged internationally, Mr Powell told reporters that there was no shortage of money but the "real challenge" would be the distribution of aid.
His trip was announced after US newspapers criticised Mr Bush for not making a public statement from his ranch at Crawford, Texas, until three days after the tsunami struck on December 26th.
Mr Powell protested that early reports of the disaster did not reflect the scope or the range of the damage and that he did not think the American people "should be given the impression that their president and government was not hard at work on this from day one".
Mr Jeb Bush, who has experience dealing with hurricane disasters in Florida, said his role was to explore long-term needs and provide a morale boost as a personal representative of the president.