Houston played host over the weekend to the annual meeting of the National Rifle Association, the gun lobbying organization many credited with helping to defeat last month's Senate vote.

Asked Monday at the White House what realistically could still be done on gun control, press secretary Jay Carney said the president remained "optimistic" that Congress would vote to expand background checks.

"We are working with Congress to explore ways of pursuing more legislative action. We are continuing in the implementation of the executive actions that the president laid out when he put forward his broad proposal. And we are looking for other ways to take action to reduce gun violence in a common-sense way that respects Second Amendment rights," Carney said.

Carney added that Obama and other White House officials were having regular conversations on gun control with lawmakers in both parties.

"But I don't have a timetable for you," Carney admitted. "That would be for the Senate to decide."