At a memorial service in Oklahoma City just days after the bombing, Clinton focused on the victims –everyday Americans who were killed simply because they went to work that day.
"This terrible sin took the lives of our American family, innocent children in that building only because their parents were trying to be good parents as well as good workers; citizens in the building going about their daily business; and many there who served the rest of us, who worked to help the elderly and the disabled, who worked to support our farmers and our veterans, who worked to enforce our laws and to protect us," he said.
Clinton tried to connect the victims to their community. "For so many of you, they were also neighbors and friends. You saw them at church, or the PTA meetings, at the civic clubs or the ball park," he said. "You know them in ways that all the rest of America could not."
McGurn said that in times of tragedy, the president represents the nation and tells those affected that America is with them.
That was a key theme in Clinton's remarks in Oklahoma City.
"You have lost too much but you have not lost everything, and you have certainly not lost America, for we will stand with you for as many tomorrows as it takes," Clinton said.
Another key moment in Clinton's presidency was the shooting massacre at Columbine High School on April 19, 1999.
A month after the shootings, which killed 12 students and one teacher, Clinton traveled to Littleton, Colo., to meet with victims' families and address students and the community.
"When America looks at Jefferson County, many of us see a community not very different from our own," Clinton said on May 20, 1999. "We know if this can happen here, it can happen anywhere."
Shesol wrote those words for Clinton. He said there was a concerted attempt for the president to "relieve the community of the burden of the singular guilt."
"This was Colorado's tragedy, but also the nation's tragedy," Shesol said.
Historian Douglas Brinkley said Obama can do something similar tonight in Tucson.
"President Obama doesn't want to isolate Arizona from the rest of the country as if there are 49 states and this is the loser state," Brinkley told ABC News. "He needs to tell people of Arizona thank you for caring, thank you for your love. It makes the people of Tucson feel special."
ABC News' Jake Tapper contributed to this report.