Large deficits and a weakened financial system have made the United States less competitive in the global economy, the World Economic Forum said in its annual review of the competitiveness of countries. The United States slipped from second to fourth in the survey, behind Switzerland, Sweden and Singapore. It had fallen from first place the year before. The study includes statistical measures as well as a survey of business owners to compare countries. In the United States, the entrepreneurs cited access to credit and government regulation among their chief concerns. But it was government debt and the country’s overall economic outlook that pushed the United States down in the rankings, said Irene Mia, senior economist at the forum, a Geneva-based think tank that sponsors the annual gathering of world leaders in Davos, Switzerland.