When his young son entered the gallery on Wednesday night, Sen. Chris Murphy (D-Conn.), was waging a filibuster in an attempt to force a gun reform vote. From the Senate floor, he offered some poignant words to the boy.

“I’m sorry I missed pizza night,” Murphy said. “I hope that you’ll understand someday why we’re doing this.”

Led by senators who represent Newtown, Connecticut — where 26 people, including 20 children, were killed in a mass shooting in 2012 — Democrats took control of the Senate floor to call for change in gun laws.

Murphy, who launched the filibuster, vowed to keep talking “as long as I can” in order to spark action that would “stem this epidemic of gun violence and in particular this epidemic of mass shootings.”

The move came three days after the Orlando attack, the deadliest mass shooting in U.S. history.

“There is a fundamental disconnect with the American people when these tragedies continue to occur and we just move forward with business as usual,” Murphy said. “So I’m going to remain on this floor until we get some signal, some sign that we can come together on these two measures, that we can get a path forward on addressing this epidemic in a meaningful bipartisan way.”

The filibuster ended at 2:11 a.m. Thursday.