In the aftermath of Monday's mass shooting at the Washington Navy Yard, Pennsylvania Republican Sen. Pat Toomey cast doubt that advocates' efforts to resurrect the debate for new gun laws would be successful.

Toomey, the co-architect of this spring's failed effort to expand background checks on gun sales, has consistently defended his work on the issue, but considerably backed off after the Senate voted it down. This week's shooting seems unlikely change that.

"The Senate spoke on this issue and we came up five votes short," Toomey said in a statement on Tuesday. "It is unclear if yesterday’s tragedy changes the atmosphere sufficiently to yield a different outcome.”

The momentum around new gun laws after the Sandy Hook elementary school massacre slowed after the background checks legislation failed. Gun control advocates were planning a lobbying trip to Washington this week to renew the push before Monday's shooting brought the topic back to the forefront.

But with Congress, and Toomey, focused on pressing economic matters this fall, gun control is unlikely to rise as a top priority, even in light of this week's deadly shooting that killed 13 people, including the gunman. Several Senate Democrats have indicated that the Navy Yard shooting hasn't moved the needle, and they would still be unable to pass a background checks bill.

In a nationally watched debate that inspired a Saturday Night Live sketch, Toomey worked with West Virginia Democrat Sen. Joe Manchin on legislation to require background checks on buyers purchasing guns online or from private dealers at gun shows. He couldn't convince enough of his Republican colleagues to support it despite adding sweetners for them strengthening protections for gun owners.

“I am still in favor of expanding background checks to all commercial sales. I voted for them in 1999," Toomey said. "I was proud to work with Senator Manchin on legislation that would have done so while also expanding the ability of Americans to exercise their Second Amendment rights."

The shooter, Aaron Alexis, bought the guns he used legally and passed two background checks, according to news reports.