By killing gun reform, the US Senate did more than deal a painfully personal defeat to Barack Obama -- it raised questions about the still ambitious president's entire second term agenda.
So far, Obama's thumping November election win has produced little of legislative substance, other than an expiry of tax cuts for the rich.
The guns reverse left the president, once the embodiment of change, puzzling over how to get a legacy-boosting program through an obstructive political system already casting an eye to the post-Obama era.
Defeated yet defiant, Obama was incredulous that the Senate Wednesday balked at expanding background checks for firearms buyers -- the final, modest but popular element of a wider gun reform drive that had already been thwarted.
"How can something have 90 percent support and yet not happen?" Obama asked rhetorically though he already knew where -- in Washington.
Obama's gun drive was based on the perception that public revulsion after the massacre in December of 20 kids in their classrooms in Newtown, Connecticut, would shift the political calculations in Washington.
Instead, it produced a lesson in the fungible nature of presidential authority, and the might of wealthy lobby groups like the National Rifle Association.
It revealed the political complexity of a town split between Democrats and Republicans, and the constraints of a political system designed as a bulwark against sudden change where piecemeal progress is the rule.
The facts of the gun defeat appear to bode ill for Obama -- after he wagered a chunk of his political capital to no avail.
"The president has definitely led many to question his ability to create a legislative majority," said Kareem Crayton, professor of political science at the University of North Carolina.
"It is not clear in a president's second term whether his turning to public pressure will be enough to convince members of Congress who are on the fence."
Despite his win in November, Obama could not get a tame gun reform measure through a Senate controlled by Democrats.
Four Democrats deserted their own president, and moderate Republicans also balked despite Obama's entreaties -- their reticence perhaps hinting at the president's limited powers of political persuasion.
The plight of Newtown appeared to touch Obama deeply and the gun debate revealed a rare glimpse of the normally buttoned up president's humanity.
But it was a fight that politically, he might have been wiser to avoid. Initially, it seemed an instinctively cautious president would.
Heading to a memorial service for Newtown victims in December, aides told reporters Obama would not make a political stir.
Yet after consoling grief-stricken families, he went all in.
"These tragedies must end, and to end them we must change," Obama said, launching the biggest debate on gun control in 20 years.
Though his response was driven by emotion, his failure was rooted in hard politics.
First, he lost four Democratic senators needed to trump Republican filibuster tactics which mean 60 Senate votes are needed to pass a bill.
Mark Pryor of Arkansas, Max Baucus of Montana, Mark Begich of Alaska and Heidi Heitkamp from North Dakota represent conservative states where gun rights are rooted in culture and self identity.
Obama complained senators ran scared of the gun lobby -- but while he is done with voters, three of those senators face tough re-election fights in 2014.
Polls still show majority support for gun reform -- but national public opinion does not automatically augur change -- and American politics does not always break down on clear party lines.
"All presidents can do is try to increase the public salience of issues," said Brookings Institution scholar Thomas Mann.
"Opposition to new measures succeeds because of the filibuster, the near unified opposition of the Republican party, and the intensity and organization of those opposing such measures."
The question is whether Obama's failure to build a decisive legislative majority on gun control will thwart other second term priorities -- immigration reform, a fair deal for the middle class and climate change.
Second term presidents quickly become "lame ducks" and the failure of gun reform suggests Obama may have trouble on other tough votes on tax hikes or climate change.
His chances are better on immigration reform.
While Republicans thwarted gun control, some party leaders are risking their careers to plot a path to legal status for 12 million undocumented immigrants.
They know that continuing to alienate Hispanics could keep their party out of the White House for a generation -- providing a powerful incentive to meet Obama in the political center ground.
But even after changing the political winds on immigration by winning millions of Hispanic votes in November, Obama knows his involvement could be toxic to Republicans, so is leaving it up to top lawmakers to get a deal.