The President might ask Congress to hold a special session to address an emergency situation.
A special session is a session outside the normal legislative session. The Constitution gives the President the power to convene both Houses or just one of them for a special meeting ( session ). This power is granted in Article II, Section 3 of the Constitution.
<em>This power is applied to deal with urgent and unexpected situations, such as war, a terrorist attack, a natural disaster or during times of economic turmoil.</em>
So far, U.S. Presidents exercised this right 28 times ( to recall both Chambers of Congress ), most recently by Harry Truman in 1948.