In her weekly press conference, House Speaker Nancy Pelosi said Republicans have a responsibility to condemn the threats against lawmakers.
Leadership, she said, has a responsibility to serve as "an example of how we express our differences and understand the impact that our words have on others. The best way to do that is to very clearly state that this is inappropriate."
"It's inappropriate for members of congress to stand up and cheer when these sentiments are expressed," she said, referring to an incident during Sunday's debate in the House when two tea partiers screamed "Kill the bill!" from the House gallery, to cheers from some Republicans. The protesters were removed from the gallery and arrested by Capitol Police.
Several Democrats have received threats of violence in the past week.
Reporting by Brian Beutler