George W. Bush (L) watches as Bill Clinton speaks during a moderated conversation at the graduation of the inaugural class of the Presidential Leadership Scholars program, a partnership between the presidential centers of George W. Bush, William J. Clinton, George H.W. Bush, and Lyndon B. Johnson at the George W. Bush Presidential Library in Dallas, Texas July 9, 2015. [Photo/Agencies]

Former US presidents George W. Bush and Bill Clinton shared a stage in Texas on Thursday to exchange quips and insights on leadership and hopes for an elevated tenor in the current presidential campaign in which their family members are running.

The two, who have become friends in retirement, told the graduation of the inaugural class of the Presidential Leadership Scholars program that failure is a part of life and to keep their ambition burning so that they can make a difference.

When it came to the presidential race in which Bush's brother Jeb is running on the Republican side and Clinton's wife, Hillary, for the Democrats, the former presidents said they wanted to see a substantive discussion of the issues facing the country and less focus on political gamesmanship.

"I know Jeb and I am confident that Secretary Hillary will elevate the discourse," Bush told the audience at his presidential center in Dallas.

"I can't attest to their surrogates. I can attest to this surrogate. I am not going to be a surrogate," he said.

"The American people expect (there) to be some sharp elbows in a campaign. What really discourages them post-campaign is the inability to govern in a way that is congenial," Bush said.