His invitation to speak at the convention came 16 years after his late father, former Pennsylvania Gov. Bob Casey, was denied a convention speaking role because of his anti-abortion views and was perceived as an olive branch to those voters.
Lawmakers also remembered Ohio Congresswoman Stephanie Tubbs Jones, a prominent Clinton supporter and longtime lawmaker, who died last week of a brain aneurysm.
"We will make certain youngsters of today will understand who Stephanie Tubbs Jones was," New York Congressman Charles Rangel, "We will change the course of this great nation of ours so that racism and sexism will not be on the agenda."
With four in 10 voters saying in the last ABC News/Washington Post poll that the economy will be their number one concern in November, the Obama campaign is trying to hammer McCain on this issue.
Meanwhile, Clinton strived to put the disunity narrative to rest in her speech.
But after a bitter primary battle with tensions between Obama and Clinton camps lingering through to the party's convention, it isn't clear how much impact her speech will have.
Senior Obama campaign officials sought to tamp down expectations, telling ABC News they can never guarantee what the reaction of everyone will be, but that Clinton's support is 100 percent.
She specifically praised the candidate's wife and potential first lady Michelle Obama -- who also praised Clinton by name during her speech to the convention last night.
The former first lady said with Obama in the White House will be "a terrific partner in Michelle Obama. Anyone who saw Michelle's speech last night knows she will be a great First Lady for America. Americans are also fortunate that Joe Biden will be at Barack Obama's side . . . They will be a great team for our country."
Analysts agree it's now in both Obama and Clinton's best interests to project a unified party as Democrats fight McCain for the Oval Office.
"I don't think she has a future as a presidential candidate if Barack Obama loses," Stephanopoulos told ABC News' Charlie Gibson. "If he loses, there's going to be so much anger in this party, I think both of them will have a hard time running again."
ABC News' David Chalian, Jonathan Greenberger, Steven Portnoy, Kate Snow, Rick Klein, and Karen Travers contributed to this report.