Obama will speak at 1 p.m. EDT from the White House.
Standard and Poor's on Friday said it was downgrading U.S. debt because the rating agency lacks confidence that political leaders will make the choices needed to avert a long-term fiscal crisis. Congress and Obama recently struck a deal to avoid a government default and to cut the deficit, although the deal was not as broad as the president wanted.
Obama is also expected to speak about Saturday's shoot-down of a helicopter in Afghanistan in which 30 U.S. troops were killed -- the deadliest incident for U.S. forces in the decade-long war.
