This week marks the six-month anniversary of the Sandy Hook Elementary School massacre, which left 26 dead and served as a rallying cry for supporters of stricter gun laws. To mark that somber occasion, gun control groups are planning to fan out across the country in hopes of jump-starting a drive for new legislation.

New York City Mayor Michael Bloomberg's gun control group, Mayors Against Illegal Guns, will launch a national bus tour starting Friday. And families from Newtown, Conn., will meet this week with members of Congress, including the House's top two Republicans, Speaker John Boehner (Ohio) and Majority Leader Eric Cantor (Va.).

Yet that renewed effort highlights the fact that Congress still hasn't passed any new gun laws. And judging by Congress' legislative agenda, as well as polls that have shown Americans returning to their past indifference on the issue, the prospect of gun control legislation getting a second wind seems unlikely.

In January, a Pew survey found that, for the first time under President Obama, more people prioritized tightening gun laws than protecting gun owners' rights, doing so by a 49 percent to 42 percent margin. However, in the months that followed, support for new gun laws slipped, quickly returning to pre-Newtown levels.

Amid the downturn in public opinion, every single gun proposal before the Senate went down in rapid succession back in April.

Following that overwhelming defeat, there was a glimmer of hope among gun control advocates that at least some of the more popular proposals, like expanded background checks, could soon come back for a second vote. That bill's sponsors, Sens. Joe Manchin (D-W.Va.) and Pat Toomey (R-Pa.), even discussed the prospect of tinkering with their bill's specific language to make it more palatable.

Since then, however, Congress has moved on to other matters, and there are no plans to bring any gun bills back for another shot. Most prominently, lawmakers are caught up in a debate over the huge immigration overhaul that has sucked up all the oxygen in Washington.

"I don't think they're going to come back on it," Arizona Sen. Jeff Flake (R), a key "no" vote on the background check bill, told the Washington Post recently. "They've got a long way to go. And frankly, I just don't see people who voted against it moving on their position."

Despite all that, groups likes Mayors Against Illegal Guns haven't give up their fight. Bloomberg's group alone has dropped over $1 million over the past few months just to attack Sen. Kelly Ayotte (R-N.H.) over her vote against the background check bill.

Vice President Joe Biden, the White House's point person on gun control, is to meet with Senate Majority Leader Harry Reid (D-Nev.) this week to talk about the issue. Last week, Biden declared that the "fight is far from over" on guns. Reid has indicated that he won't bring any gun bills back for a vote unless he knows he has the 60 votes necessary to move them along.

As for President Obama, he issued 23 executive orders back in January related to guns. But since then, he's done little else besides beg Congress to act. And according to the Associated Press, his aides have said there are no plans in the works for new executive actions.

In a sign of how the national mood has changed since Obama issued those orders in January, there was virtually no public outcry after a gunman last Friday killed four people in Santa Monica, Calif. After the attack, the president's former deputy press secretary Bill Burton remarked that the silence in itself was indicative of how far we had come from Newtown.

In lieu of federal action, gun control advocates have focused their efforts on the states. On Tuesday, supporters of background checks submitted a ballot initiative that would expand Washington state's oversight of online and private sales.

But even at the state level, advocates of stricter gun laws have increasingly found themselves on the defensive. The NRA filed a lawsuit against New York over its new gun restrictions, and some 1,000 protesters demonstrated against the law in Albany on Tuesday.

"Bottom line: The raw politics of the gun debate haven't changed," the Washington Post's Ed O'Keefe wrote Tuesday, "and any new push this week by the victims of gun violence — however emotional it may be — is more likely to just remind Americans that Congress hasn't addressed the issue rather than actually compel lawmakers to act."