President Obama was visibly frustrated on Thursday night as he offered the latest in a long series of responses to a mass shooting in America.

At the core of his speech was a call to action. Tightening gun laws, he said, "will require that the American people, individually — whether you are a Democrat or a Republican [or] an independent — when you decide to vote for somebody, are making a determination as to whether this cause of continuing death for innocent people should be a relevant factor in your decision. If you think this is a problem, then you should expect your elected officials to reflect your views."

In other words: Vote for politicians who will vote to change the law.

As frustrated as he was on Thursday, it paled next to his fury on April 17, 2013, when he went to the White House Rose Garden to respond to a Senate filibuster that killed an increase in background checks that polling showed had broad public support. "[T]his was a pretty shameful day for Washington," he said, before issuing a call similar to the one above. "To all the people who supported this legislation — law enforcement and responsible gun owners, Democrats and Republicans, urban moms, rural hunters, whoever you are," he said, "you need to let your representatives in Congress know that you are disappointed, and that if they don’t act this time, you will remember come election time."

Come election time November 2014, the Republican Party that supplied nearly every vote to protect that background check filibuster took control of the Senate and expanded its House majority, which is now as big as at any point since the Great Depression.

If past patterns hold, we're going to see a burst of attention paid to enacting new gun laws over the next few days — though it seems as though the fervor for advocating for political change in the wake of shootings has diminished. You'll hear reference to the fact that more than 90 percent of Americans support requiring background checks for all gun buyers, which is true. In fact, that figure is up since 2013 in polling from Quinnipiac University.

But contrast it with these figures, also from Quinnipiac.

The public supports background checks, but opposes stricter gun laws. This makes the job of opponents to expanded background checks pretty easy: Point out that it's a stricter gun regulation.

Polling from CBS News in August went a step further, asking if Americans supported strengthening or loosening gun laws. Most people support stricter laws, but a sizable group is happy to keep laws as they are.

On top of that is layered two groups of advocates: those pushing for new gun laws and those opposed to such a move. The latter group is represented by the National Rifle Association and Gun Owners of America. The former is represented by -- well, now there's Everytown for Gun Safety, the evolution of Michael Bloomberg's work on gun legislation when he was mayor of New York. That you might not have heard of it makes clear one key challenge.

It's often argued that the NRA has a stranglehold on Capitol Hill thanks to its lobbying and campaign donations. While the organization and its political arm are obviously active, that's probably an underestimation of the activism against gun laws. In 2013, the Pew Research Center revealed data proving what's probably an obvious point: gun-control opponents — often but not always mobilized by gun groups — are more likely to be politically involved and to vote on the issue.

There are a number of other factors that come into play as well. The NRA is reviled on the left but respected on the right. In fact, it's one of the most popular political organizations in the country — bolstering its political weight. Gun rights has become one of the most polarized topics in politics, making it harder for Republican and Democratic representatives to break with their parties on the votes. Breaking with the party doesn't necessarily pay immediate dividends, either. Of the four Democrats who broke with their party to oppose the 2013 background-check measure, three are no longer senators. Two were voted out.

The picture, then, is this: A Republican-controlled Congress in which Republican support for gun rights is a litmus test, and gun rights advocates are more willing than opponents to take political action. That's on top of an electorate that is generally favorable toward new gun legislation, but not always passionately so.

Obama's message to gun control advocates in 2013 and this week was the same: We need to change Congress. That's the last and biggest stumbling block. To change Congress, he needs people to vote gun-control advocates into office in red states and districts. Of course, one of the few things that's more polarizing than gun control is Obama himself, meaning that one of the worst possible messengers to inspire Republicans to vote against their party on guns is Barack Obama.