Exasperated gun control advocates in the Senate said they remain several votes short of what is needed to pass tougher background checks to prevent felons and the mentally ill from buying guns.
"We don't have the votes," Senate Majority Leader Harry Reid, D-Nevada, who earlier led the Senate in a moment of silence for the victims of the tragedy. "I'd like to get them but we don't have them now."
"I don't know when enough is enough," said Sen. Dianne Feinstein, D-California, who after the Sandy Hook Elementary School massacre last year in Newtown, Connecticut, last year led an unsuccessful effort to toughen gun laws.
She said she is "not optimistic" the Navy Yard shooting would do enough to change the political equation in Congress where most Republicans and several Democrats remain wary of new gun laws.
In response to Newtown, Sen. Joe Manchin, D-West Virginia, tried to pass compromise background check legislation but it fell five votes shy on a vote in April.
He said he wants to wait for the facts to come in on the Navy Yard shooting before making a push to vote again on his bill because it would be "ridiculous" to have senators vote on it again "if we don't have the support."
Manchin hopes Democratic senators, like Max Baucus of Montana and Mark Begich of Alaska, and Republican senators like Saxby Chambliss and Johnny Isakson of Georgia and Lisa Murkowski of Alaska, who voted against his bill before might change their minds and support it in the future.
Family members of Newtown victims will be on Capitol Hill Wednesday lobbying lawmakers to support tougher background checks. Their visit, which comes nine months after that incident, was planned before the Navy Yard shooting.
Republican Sen. Lindsey Graham of South Carolina didn't point to gun control when he was asked about the 12 fatalities at the Navy Yard at the hands of a sub-contractor who gained access to the base legally.
"My question is how do people get hired? It's not the weapons so much as how did he pass the security clearance? What kind of security screening do we have that we give secret clearances and jobs on important navy facilities? That to me is the bigger question," he said. "I don't think anything has changed about guns."
CNN's Dana Bash, Lisa Desjardins, and Becky Brittain contributed to this report.