Billions of dollars in the budget for the U.S. Defense Department is on the line should members of the U.S. Congress fail to act on economic policy before a March deadline.
National security is at stake without a balanced budget approach that embraces "sensible changes" to social welfare programs and tax codes, Obama said.
"As our military leaders have made clear, (budget) changes like this affect our ability to respond to threats in an unstable part of the world," he said. "And we will be forced to make even more tough decisions in the weeks ahead if Congress fails to act."
Obama said Republican leaders were holding too firm to tax loopholes that could benefit the wealthy.
The military last week delayed deployment of naval assets to the Persian Gulf, citing budgetary constraints.
U.S. Defense Secretary Leon Panetta said looming budget cuts are one of the greatest threats to national security.
House Speaker John Boehner, R-Ohio, said budget issues could be addressed "not with further tax increases on the American people but with responsible spending cuts that will help balance the federal budget within the next decade."