Rep. Seth Moulton (D-Mass.) refused to take part in a moment of silence for the victims of the largest mass shooting in U.S. history that occurred in Las Vegas Sunday night.
“Now is not a moment for silence; it's a time for action," the congressman tweeted.
Moulton was joined by Rep. Katherine Clark (D-MA), who also boycotted.
Moulton took a shot at House Speaker Paul Ryan on Tuesday, telling him to "do your job" and vote on gun legislation, and that he is "letting America down."
He and several Democrats also refused to stand for a moment of silence for the victims of the June, 2016 Pulse nightclub shooting in Orlando, Florida.
The Democrat is an outspoken gun control advocate, and has pressed Republicans to take up gun control legislation.
The gunman, 64-year-old Stephen Paddock, opened fire on a country music concert from his room on the 32nd floor of a nearby hotel. The attack killed 59 people and injured over 500.