President Barack Obama plans to honor victims of gun violence in his State of the Union address next week by leaving a seat empty in the first lady's viewing box.

On a phone call with supporters, Obama said he hopes the empty seat will be a reminder of those who have been killed, and a message to Congress to act.

He says, "Their absence means something to this country."

Presidents have long invited prominent individuals and average Americans to sit with the first lady, often as a way to underscore a theme.

Obama is expected to make the case for tougher gun control laws in the speech.