Question

When might the president ask congress to hold a special session

Answer 1

The president request that congress hold an special session when the two houses can't concede to a date to meet or in a emergency circumstances. 

Answer 2

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.

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.

So far, U.S. Presidents exercised this right 28 times ( to recall both Chambers of Congress ), most recently by Harry Truman in 1948.