Obama: Income inequality defining challenge for US

US President Barack Obama on Wednesday said income inequality is the "defining challenge" for the United States, while a growing middle class is the engine of US economic prosperity. The rich Americans took a disproportionately large portion of wealth and the U.S. society is getting increasingly unequal, Obama said during an event hosted by the Washington-based think tank the Center for American Progress. The challenge is posing a "profound" threat to the American Dream and it is an issue that Washington should tackle seriously, he said. The income inequality is hurting the country's middle class and the "opportunity gap" in the United States is growing, noted Obama, adding the world's largest economy needs a growth strategy. Obama used the opportunity to press Congress to raise the national minimum wage currently at 7.25 US dollars per hour in an effort to help low-wage workers and boost economic growth.