Under the statute, mandatory caps start in 2013 with $546 billion for defense and $501 billion for nondefense.

The caps actually rise every year, and in 2021 reach $644 billion for defense and $590 billion for nondefense.

But the amounts are “scored” in budget accounting terms as reductions, because they are lower than the amounts now projected for those future years.

Obama and Democratic congressional leaders blamed Republicans for the committee’s inability to reach an agreement, and said lawmakers  have a year to come up with a new plan before the mandatory reductions kick in.

Obama also noted that some members of Congress “are trying to undo these automatic spending cuts,” but he pledged, “I will veto any effort to get rid of those automatic spending cuts to domestic and defense spending. There will be no easy off-ramps on this one.”

Republicans said Democrats were at fault for the stalemate in the supercommittee. Senate Minority Leader Mitch McConnell (R-Ky.) said, “In the end, an agreement proved impossible not because Republicans were unwilling to compromise, but because Democrats would not accept any proposal that did not expand the size and scope of government or punish job creators.“

(Updated 11/22/11 to correct official name of committee.)