An exhausted Mark Kelly, left, husband of Rep. Gabrielle Giffords, exchanges words with President Barack Obama following the president's speech during the visit of President and Mrs. Obama to Tucson, Ariz., on Jan. 12, 2011, for a memorial event, "Together We Thrive: Tucson and America," to honor the victim's of Saturday's mass shooting. Kelly Presnell/Arizona Daily Star

President Obama told grieving relatives earlier this week that he had no words to express the loss Tucson suffered in a few awful moments on Saturday.

He found those words Wednesday night in his first official visit to Tucson, urging a capacity crowd at McKale Center to build an America that is worthy of 9-year-old Christina-Taylor Green, whose hopeful vision of democracy had not yet been dimmed by political vitriol.

"I want to live up to her expectations," he said. With applause swelling, the crowd was on its feet by the time he thundered, "I want our democracy to be as good as Christina imagined it."

More than 13,000 people crowded into McKale Center. When that filled up, a similar number filed into Arizona Stadium.

Many had been there for hours, bringing their bottled water, their ballcaps and their broken hearts. A town of about 1 million felt like a community, with people striking up friendships in line.

But while it might have been seeking balm, Tucson was not in the mood to be somber.

At times during the "Together We Thrive" event, the crowd bordered on raucous, making the early part of the service feel like a rally.

Generous with bipartisan applause, it exploded when Demo-cratic Sheriff Clarence Dupnik showed up on the Jumbotron. It did the same for U.S. House Democratic Leader Nancy Pelosi and for former Gov. Janet Napolitano, who also merited a "We miss you!" from a woman in the McKale audience.

But the crowd also applauded for Republican U.S. Sens. John McCain and Jon Kyl, and supported Gov. Jan Brewer, who said the tragedy didn't just take six lives, but, "It pierced our sense of well-being."

This state, she pledged, "will not be shredded by one madman's act of darkness."

The tears flowed more freely when the president spoke.

Obama told members of the crowd that they may be mourning, but there is reason for hope.

A few minutes after he left the hospital room where U.S. Rep. Gabrielle Giffords is recovering from a gunshot wound to the brain, he said, Giffords opened her eyes for the first time.

The crowd erupted. Michelle Obama grabbed the hand of Giffords' husband, Mark Kelly, who then turned to Napolitano for a hug.

"She knows we are here. She knows we love her, and she knows we are rooting for her through what we know is going to be a difficult journey," Obama said.

The president cited the heroism of Giffords intern Daniel Hernandez Jr., a UA student who helped save his boss's life.

He cited the heroism of the men who tackled the gunman and of the woman who wrested the ammunition away.

And he applauded the first responders and doctors working to save lives.

"These men and women remind us that heroism is found not only on the field of battle," he said. "They remind us that heroism does not require special training or physical strength.

"Heroism is here," he said, "all around us."

Obama implored the crowd to take lessons from the tragedy.

At a time when political discourse remains sharply polarized, he said, "It's important for us to pause for a moment and make sure that we are talking with each other in a way that heals, not a way that wounds."

He said that while it's impossible to know what triggered the attack, it is important to examine the facts behind it. "We cannot and will not be passive in the face of such violence," he said. "We should be willing to challenge old assumptions in order to lessen the prospects of violence in the future."

But what we can't do, he said, "is use this tragedy as one more occasion to turn on one another."

One by one, he went through the list of victims. George and Dorothy Morris, as well as Dorwan and Mavy Stoddard - couples who were so in love but have now been torn apart - remind us of our spouses and partners, he said. Phyllis Schneck was like our collective grandmother or mother, he said, while 30-year-old Gabe Zimmerman was like a brother or son. Judge John Roll embodied "America's fidelity to the law," he said, while Giffords is a reflection of public spirit.

"Those who died here, those who saved lives here - they help me believe," he said. "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."

But if he described the others as family members, he described Christina-Taylor as our conscience.

In closing, Obama mentioned Christina-Taylor was among 50 babies born on Sept. 11, 2001, pictured in a book called "Faces of Hope," which printed simple wishes for the children pictured, from hoping they would know the words to the National Anthem to hoping they would jump in rain puddles.

"If there are rain puddles in heaven, Christina is jumping in them today," Obama said. "And here on Earth, we place our hands over our hearts, and commit ourselves as Americans to forging a country that is forever worthy of her gentle, happy spirit."

Among the onlookers was Jerri Boerum, a 37-year-old paralegal who kept her two school-age children out of school to attend the event, along with her 2-year-old.

"It's very important as a community and for my children to see the community come together like this," Boerum said. "What we saw on the news on Saturday was very scary. It's not what we're used to in Tucson."

Boerum had met Giffords in previous political events.

Seeing the size of the crowd, she hoped, will show her children "that sometimes evil will tear us down, but together we can build something better."

Topher Hatton, a 30-year-old student working on a business degree, echoed those sentiments.

"I think this will make everybody come together," predicted Hatton, who showed up at 9 a.m., equipped with camp chairs and food. "We are like siblings. We fight sometimes, but at the end of the day, we have to all make up and get along."

Elizabeth Hickman, a 34-year-old homemaker, brought her children as well. Her friend works for the Safeway grocery store where the rampage took place. She'd left early that day. Her teenage son's best friend works there, too. He was scheduled to be on at 11 a.m. and drove into the parking lot to find it filling with emergency vehicles.

"It's the what-could-have-happened that gets me," she said, with a visible shudder. She had planned to bring her children to the memorial shrine blooming in the lawn at University Medical Center, but then discovered Obama was coming. "I think it just shows how we can all come together."

Edgar Sandoval, 18, a Pima Community College student, praised the speech afterward. "He was really there for Tucson. I'm proud that he came," he said, adding the part about helping each other and finding common ground instead of blaming others really resonated with him.

Kaitlyin Simpson, a UA communications major from Phoenix, agreed. "The fact that he focused on the victims and made it about their lives and the good things they did for this community was great. He put a positive light in Tucson in a time of need."

Ross Zimmerman, Gabe Zimmerman's 58-year-old father and an IT network analyst at Pima Community College, said earlier in the day that he hopes it helped.

"I think it's a very good thing that something this terrible can happen, and the highest elected official in the country will drop what he's doing to come be with us and grieve with us," said Zimmerman, whose family received a call from Obama earlier in the week.

"It's a good thing he's helping us get through this - because we have no choice but to go on and get through this."

Reporter Becky Pallack contributed to this story. Contact reporter Rhonda Bodfield at at 573-4243.