While richer nations sometimes pay for their own aid projects , Robert B. Zoellick , the president of the World Bank , said when the gifts were announced on December 15 , 2007 , that World Bank money `` is the core funding that the poorest developing countries rely on '' . While wealthier nations sometimes fund their own aid projects , including those for diseases , and although IDA is the recipient of criticism , Robert B. Zoellick , the president of the World Bank , said when the gifts were announced on December 15 , 2007 , that IDA money `` is the core funding that the poorest developing countries rely on '' .