The president inserted his speech's most dramatic line - that Rep. Gabrielle Giffords had opened her eyes for the first time - only moments before taking the stage at McKale Center. KELLY PRESNELL / ARIZONA DAILY STAR

WASHINGTON - There are moments that define a presidency, and Barack Obama's speech Wednesday night to a memorial service for Arizona shooting victims may be one.

First in a moving eulogy to those who died, then in the uplifting tales of those who acted heroically, finally in his call to the nation to live up to the ideals of a slain 9-year-old girl, Obama recaptured, at least temporarily, the appeal that first thrust him onto the national stage - the sense that the country is a family that yearns to be united, not divided.

"It reminded us of how he got to be president," said Wayne Fields, an English professor at Washington University in St. Louis and an expert on presidential rhetoric. "It wasn't because of something he was. It was something that we longed for. That was to be whole."

Obama's speech was born of tragedy in Saturday's shooting rampage in Tucson that killed six and injured 13 others, including Rep. Gabrielle Giffords, D-Ariz. All were gunned down while participating in one of the most basic rituals of American democracy - ordinary people meeting with their member of Congress.

Obama wrote many of his remarks himself. He was still making changes after landing in Arizona Wednesday afternoon, and inserted its most dramatic line backstage just minutes before walking into the University of Arizona's McKale Center.

That was his revelation that the critically injured Giffords had opened her eyes just minutes before, something he learned from her husband on the short limo ride from hospital to arena. People in the arena cheered and cried at the news.

"A powerful moment," Fields said.

Obama started the speech with what amounted to a eulogy for the fallen, telling in simple words the stories of those who'd been killed.

Obama built to a crescendo of sorts when he turned finally to the story of Christina-Taylor Green, the precocious 9-year-old who was interested in public service and was killed while waiting to meet her congresswoman.

"I want our democracy to be as good as Christina imagined it. I want America to be as good as she imagined it," he said.

Obama, who has two daughters himself, looked down and appeared to pause to control his emotions at one point while speaking about Christina.

It was a rare glimpse of the personal in a president whose cool demeanor - critics call it a disconnect - stands in contrast to the more emotive Bill Clinton or George W. Bush.

"He was more emotional than I've seen him," said Martha Joynt Kumar, a scholar of presidential communications from Towson University in Maryland.

"He was very real, very genuine."

Watching the speech on TV at a Washington restaurant - the major networks interrupted entertainment programming to show Obama's remarks - Kumar said patrons had tears in their eyes.

"The nation stopped," she said. "People stopped and listened and felt the tragedy."

For Obama, the speech offered a chance to return to a theme he has talked about periodically, the need for a more civil and less partisan politics. That was the message he delivered as an Illinois state senator at the 2004 Democratic National Convention - the speech that made him a national star - and it also drove much of his appeal in 2008.

Even one of his most vocal critics, talk show host Glenn Beck, lauded the speech.

"This is probably the best speech he has ever given, and with all sincerity, thank you Mr. President, for becoming the president of the UNITED States of America," Beck said Thursday.

It also allowed Obama a new chance to connect with the American people at a moment of maximum exposure.

"Every president begins his term with the almost undivided attention of the American public. But that window of opportunity shrinks almost every day. A moment like this re-expands that window of opportunity," said Dan Schnur, director of the Jesse M. Unruh Institute of Politics at the University of Southern California.

"He's always been criticized for being emotionally distant. This may have been the first opportunity since his election to redevelop an emotional connection with voters. … By giving a nonpolitical speech, he gave himself an opportunity to benefit politically."