In a brief statement from the White House, Mr.Obama stressed this will be a complex and challenging operation.

VOA: standard.2010.01.13

Despite some of the most challenging economic conditions in decades, American consumer confidence jumped unexpectedly this month, a sign that widespread pessimism might be dissipating.

VOA: standard.2009.08.25

It is a long-term endeavor and we both are united to fight against this endeavor, which is challenging our way of life and wants to challenge the way of life with the world."

VOA: standard.2009.05.13