Our nation came together Tuesday morning over a collective outrage, an egregious injustice, a nationally televised attack upon all that is decent and fair in America. As must surely be clear now to the National Football League, if you really want to feel the collective wrath of the American people, just start messing with their football.

Late Monday night, and well into Tuesday, the country aimed its anger directly at the NFL, the beloved behemoth of American sports franchises, over the blown call on the game’s final play that gave the Seattle Seahawks the winning touchdown over the Green Bay Packers on ESPN’s “Monday Night Football.”

Three weeks’ worth of criticism and angst over the subpar performances of the NFL’s replacement referees — filling in for the league’s regular ones, who have been locked out by the league in a labor standoff — reached a boiling point when the refs appeared to blow the biggest call of the game, awarding the Seahawks a touchdown on the final play, and thus a 14-12 win, when everyone else in the country seemed to know immediately it was an interception for the Packers.

“Terrible,” President Obama told reporters in response to a question about the game’s ending. “I’ve been saying for months, we’ve gotta get our refs back.”

With the league already teetering on the edge of chaos and mutiny over the state of the officiating over the first three weeks of its regular season, Monday night’s fiasco carried the distinct feeling of a tipping point. The story led NBC’s “Today” show, exploded across Twitter and dominated discourse around water coolers and radio dials.

Not only had the 3½-month lockout of the referees by the NFL’s owners — primarily over the officials’ pensions — reached a critical juncture, where something had to be done for the good of the game and the safety of the players; it also felt as if the NFL was collapsing into itself.

“DISGRACE!” screamed the back page of the New York Post.

“Nightmare scenario,” blared the headline on SportsIllustrated.com.

“The Straw That Broke the NFL’s Back,” touted one of the headlines at ESPN.com.

The NFL’s locked-out referees, although technically part-time employees, undergo rigorous training to master the league’s infamously complex rule book. Their replacements, largely a collection of officials who work high school and low-level college games, have often seemed out of their depth during the first weeks of the season. But no games had been blatantly decided on a blown call — until Monday night.

With the Seahawks trailing, 12-7 and eight seconds remaining, quarterback Russell Wilson launched a 24-yard “Hail Mary” pass into the end zone. Packers safety M.D. Jennings appeared to wrest control of the ball from Seahawks wide receiver Golden Tate — an interception — but one of the referees near the play threw up the signal for a touchdown.

As players, coaches, fans and television viewers waited anxiously, the referees reviewed replays for some 10 minutes — and still got it wrong, saying Tate had shared possession of the ball, which, by rule, favors the offensive player. The touchdown stood, the Seahawks had prevailed by a 14-12 score, and the universe, at least as measured in terms of Twitter and talking-head outrage, was about to explode.

“The NFL is too good for this, too big for this,” said Steve Young, an ESPN analyst and former NFL quarterback who was at the game. “It’s too hard to watch.”

“I love this league and love the game of football,” tweeted New Orleans Saints quarterback Drew Brees, one of the most widely respected players in the game, “but tonight’s debacle hurts me greatly. This is NOT the league we’re supposed to represent.”

An outraged Jon Erpenbach (D), a Wisconsin state senator, tweeted the office telephone number of NFL Commissioner Roger Goodell three times, adding, “If tonights [sic] game doesnt make the NFL settle with the real refs this season will be a joke.”

On MSNBC’s “Morning Joe” program, former president Bill Clinton was asked about the game.

“I would not have called that last play the way they did in that Seattle-Green Bay game last night,” Clinton said. “The Packers will wake up this morning and just sort of shake their head and say: ‘We should have won by two touchdowns.’ ”

By midday Tuesday, the reaction across the game was only slightly more muted. The NFL released a statement shortly after noon upholding the referees’ decision(but adding that Tate should have been flagged for pass interference for shoving a Packers defender on his way up).

The statement gave no indication of when the league might settle its dispute with its regular officials, or whether there was any sense of urgency to do so. However, the NFL and representatives for the referees were said to be negotiating Tuesday, although people familiar with the talks said they had been scheduled before Monday night’s episode.

“It’s like putting a bunch of college players out there to play an NFL game,” Washington Redskins cornerback Josh Wilson said by telephone Tuesday, speaking of the replacement referees. “These are amateur people doing professionals’ jobs. It’s not good for the integrity of the game.”

Indeed, the referee (technically the side judge) who signaled touchdown at the end of Monday night’s game was revealed to be one Lance Easley of Santa Maria, Calif., who, according to the Santa Maria Times, worked junior college and high school games along California’s Central Coast before the NFL hired him as a replacement.

On a fundamental level, all sports rely on the credibility of its games’ outcomes to sustain fan interest. If fans can’t trust that the winner and loser were decided fair and square, the fabric of the sport unravels — which is why the 1919 Chicago “Black” Sox gambling scandal, a handful of college basketball point-shaving scandals of the past 50 years and doping scandals in baseball, cycling and Olympic sports were so damaging.

That trust is even more important for the NFL, because it is by far the most popular sport for gambling, legal and otherwise. Various estimates Tuesday suggested that anywhere from $150 million to $500 million switched hands thanks to Monday night’s outcome, based upon the fact the Packers had been 3½-point favorites at kickoff.

“I think [the officiating problem] is extremely damaging for the league’s image,” Scott Minto, director of San Diego State University’s Sports MBA Program, said Tuesday, “and if [the NFL is] not careful, it can be damaging for business.”

Critics of the NFL typically focus on the game’s violence as the biggest threat to the league’s supremacy on the American sports landscape. But judging from the level of outrage over Monday night’s game, the NFL may have an even bigger and more destructive existential crisis on its hands if it doesn’t strike a deal with its referees soon.

Mark Maske and Mike Jones contributed to this report.