"Congress has failed to act because it's filled with too many lapdogs for the gun lobby," said Dan Gross, president of the Brady Campaign to Prevent Gun Violence.
The criticism was made after a young white man shot dead nine black worshippers in a church in Charleston, South Carolina.
Dylann Roof has been charged with nine counts of homicide and illegal possession of a firearm following Wednesday’s night shooting.
Chelsea Parsons, who oversees gun policy for the liberal Center for American Progress, said the new shooting would have no impact on Congress.
"I'd like to say these shootings in Charleston will be a turning point, enough for Congress to fight back against the gun lobby and take some serious action about gun laws. But I don't want to be naive," Parsons said.
Democratic Senator Chris Murphy blamed the powerful National Rifle Association for Congress' failure to restrict guns.
"I'm skeptical it's going to change peoples' minds who weren't converted by Newtown," he said.
The senator was referring to another mass shooting in the United States.
In December 2012, twenty children and six adults were fatally shot by a gunman at the Sandy Hook Elementary School in Newtown, Connecticut.
Since the Newtown slaughter, President Barack Obama has pushed for gun law reforms, including expanded background checks and a ban on high-capacity magazines. However, the powerful gun lobby and its supporters in Congress have blocked the proposed measures.