In fact, Florida's junior senator finally seemed more like the substantial political figure he's long had the potential to become.

Marco Rubio rightly said Wednesday night that the guts he showed in standing before a grief-wracked crowd to defend gun policies six days after Florida high school massacre paled against the remarkable courage shown by the bereaved.

But it took steeliness that is unusual in the current crop of politicians nonetheless, as Rubio faced a searing cross-examination from relatives and friends of those who lost loved ones, and defended policies hewed from the orthodoxy of the National Rifle Association.

Rubio's comments over the past week were blasted as "pathetically weak" by Fred Guttenberg -- whose daughter Jaime was shot in the back as she ran. The Florida senator heard jeers and boos when he refused to say he would reject NRA campaign cash in the jarring emotional bear pit of a CNN town hall event.

Rubio insisted that the plague of school shootings could not have been solved by new gun laws alone in an electrifying exchange with Guttenberg, taking his punishment, looking his inquisitor in the eye and respectfully saying "yes, sir."

Yet even among those who vehemently disagreed with him, Rubio did get credit for showing and testing his arguments against an outraged crowd and for displaying a glimpse of political flexibility under political fire.

"I would just like to thank you again for coming out and listening to us because that's a lot more than what can be said for our so-called president and governor," Chris Grady, a student at Marjory Stoneman Douglas high school, told Rubio.

At times, Rubio appeared to be enduring a cathartic political experience, reconciling his own beliefs on gun control that he has held since entering winning his first public office, on the West Miami City Commission 20 years ago, with the fury of many in the crowd.

In a sign of the pressure exerted by the intense movement that is emerging to make sure this mass shooting does not result in the same policy inertia as all the rest, Rubio also broke with President Donald Trump and the NRA on several key issues.

He said he backs raising the age someone must be to buy a rifle or shotgun to 21, a position that the gun lobby group has rejected. As a father of high-schoolers, he opposed Trump's idea to arm some teachers. He said he was reconsidering his opposition to proposals to limit the size of gun magazines.

These were small breaks from the creed of gun rights advocates who dominate the GOP and do not mean that Rubio will lead a charge for reform in Congress. But they were concessions that pose some risk for the Florida senator.

JUST WATCHED Rubio: I support raising age limit on rifles Replay More Videos ... MUST WATCH Rubio: I support raising age limit on rifles 01:44

With that in mind, he delivered the most memorable line of the night by a politician, which amounted to an indictment of the polarization of public life.

"American politics is the only part of our lives where changing your mind based on new information is a bad thing," he said.

Of course, while his decision to show up is worthy of respect, Rubio also had political motivations to attend. Had he not gone, his absence would have been glaring, with his fellow Florida senator, Democrat Bill Nelson, on stage. The Sunshine State's governor, Rick Scott, is already facing the heat that Rubio avoided by being there after he declined an invitation.

And on Twitter after the town hall, Rubio seemed less like the brave figure on stage on Wednesday night and more like a conventional GOP politician trying to protect his conservative flank.

"Banning all semi-auto weapons may have been popular with the audience at #CNNTownHall, but it is a position well outside the mainstream," Rubio tweeted.

Banning all semi-auto weapons may have been popular with the audience at #CNNTownHall, but it is a position well outside the mainstream https://t.co/18rMDwEfGs — Marco Rubio (@marcorubio) February 22, 2018

Rubio, a hip-hop-loving 40-something, has always marketed himself as a new kind of Republican who could sell conservatism to a new generation, so he can ill afford to ignore the turbulent activism capturing young people in the aftermath of the shooting in his state — even if he does not have to run for re-election until 2022.

In a narrowly political sense, Rubio was more relevant on Wednesday night than he's been since his humiliating dismemberment in the 2016 Republican primary race by Trump. It would be crass to say that this terrible moment might help relaunch his political career, but there was certainly a sense that the self-examination he went through on stage might lead him to the purpose he has sometimes seemed to lack since returning to the Senate.

Ever since Rubio first entered Florida politics and rose to become speaker of the state House of Representatives, he's caught buzz as a possible future President. Many in the GOP believed that 2016 was his moment.

But slick political skills and his self-image as a Ronald Reagan-style optimist for the 21st Century was a poor fit for the stark Republican mood that brewed Trump's populist nationalism.

Rubio was, in effect, running for the nomination of a Republican Party that no longer existed. When he finally got down in the gutter with Trump, he was crushed, and earned the humiliating nickname "Little Marco."

Rubio has often disappointed his fans in the Washington pundit class, and it its too early to tell whether Wednesday night marked a true evolution in a political career that is in a rehabilitative stage.

But by showing up at an event where he was cast by circumstance as the villain, he showed a side of his political character that many people had forgotten was there, or doubted existed at all.