Former U.S. presidents George W. Bush and Bill Clinton told a forum in Dallas on Thursday that they were able to forge mutual bonds of respect and friendship because the other had been gracious in victory and respectful of presidential power.

The two did not mention President Donald Trump once during a nearly hour-long discussion where they traded quips and insights. But they offered indirect references that many in the crowd of about 300 people at the George W. Bush Presidential Library took to be references to the current president.

"He (Clinton) was humble in victory, which is very important in dealing with other people," Bush said at the event to mark a graduation at the Presidential Leadership Scholars program, a partnership among the Bush, Clinton, Lyndon Johnson and George H.W. Bush presidential centers.

Clinton said: "If you want to be president, realize it’s about the people, not about you.

"You want to be able to say 'things were better off when I quit, kid’s had a better future, things were coming together.' You don’t want to say, ‘God, look at all the people I beat.'"

Current President Trump has come under criticism from Democrats who have said he fires off excessive and unwarranted criticism against his predecessor, Democratic President Barack Obama and the person he beat in the election, Democrat Hillary Clinton.

Republican Bush said while in office he sought Democrat Clinton's advice. Clinton said when he left office he told incoming President Bush that he would offer him help and treat him with respect.

Bush and Clinton said they have enjoyed their lives after the presidency but would not trade their current status for their eight years in office.

"The decisions you make have a monumental effect on people,” Bush said, adding humility is a key quality for any president.

“Presidency is often defined by the unexpected. It makes the job interesting," he said.

Clinton said: "If you don’t deal with the incoming fire, it will undermine your ability to do anything else. If all you deal with is incoming fire, you can’t keep the promises you made when you were running."

The two also exchanged jokes about being grandfathers, with Bush saying his grandchildren call him "jefe," Spanish for "chief."

"The best thing that can happen to you when you are in politics is to be consistently underestimated," Clinton said.

"I was pretty good at that," Bush returned.