In Congress, the political terrain on guns can be divided into two camps on each side of the aisle: Democrats firmly for tough gun-control measures and those who are more circumspect; Republicans firmly against most gun-control efforts and those who are willing to deal.

At this stage, here’s how it appears to break down:

Roughly 130 Democrats are seen as hard-core supporters of firm gun-control measures.

“We’ve been here before trying to pass meaningful gun legislation, but I think giving it another try is better than an alibi, and I would hate to have another mass killing and say we didn’t even try to do anything,” said Rep. Emanuel Cleaver, D-Mo.

The question for them this year is how far to push. They know that the public mood is changing, but whether the politics will follow is unclear. Recent polls that found growing support for gun control measures have made them hopeful.

“The American public has had it,” said Rep. Nita Lowey, D-N.Y.

On the other hand, the latest Gallup poll found that dissatisfaction with the current gun laws, while up, is still only at 38 percent.

“This is heavy lifting, and it’s going to take time,” said Rep. Carolyn McCarthy, D-N.Y., one of the House’s leading gun-control advocates. “Are we going to waste time on heavy lifting, or spend time on things that could get passed?”

There are also Democrats who might not yet be persuaded to support some restrictive measures, but could be. That’s the role of Rep. Mike Thompson, D-Calif., a gun owner and hunter who’s been chosen to lead a task force on the issue. Thompson, who calls himself a “combat veteran who carried an assault rifle in Vietnam,” is also clear on how far he’s willing to go.

“Military-type assault weapons and assault magazines have no place on our streets and in our communities,” he said.

Any legislation the House would consider has to go through Republican committee chairmen or leadership, and that’s going to be tough.

“I don’t know yet,” said Rep. Fred Upton, R-Mich, the chairman of the House Energy and Commerce Committee, when he was asked whether the public mood has changed.

This bloc remains unconvinced. Rep. Raul Labrador, R-Idaho, said an assault ban was “not something that would actually protect people at this time.”

Rep. Trey Gowdy, R-S.C., told Fox Business Network, “They want to pick on the bastard child of the Bill of Rights, which is the Second Amendment, and it’s not going to happen, not on my watch.”

Rep. Steve Stockman, R-Texas, is endorsing “Gun Appreciation Day” Saturday, an effort by gun rights groups to have people show support by turning out in big numbers at gun stores, ranges and shows.

"It’s great to see Americans standing up for their constitutional rights," he said.

Gun control measures have fared well among Republicans in urban areas, notably New York, New Jersey and New England. But Republican ranks in that region have diminished in recent years as the party has grown more conservative.

Lindsay Wise contributed to this article.