Former president Jimmy Carter joked with his former vice president Walter Mondale in a Washington hotel ballroom Tuesday evening, as the two pondered the state of global human rights, the importance of diplomacy and a historic partnership that reshaped the presidency.

Carter, 90, joined Mondale,  87,  for an informal chat during a "Celebrating Fritz" dinner at the Four Seasons Hotel that was both a seminar on governance and a fundraiser to support the University of Minnesota's Humphrey School of Public Affairs where Mondale teaches.

About 400 guests, including those who worked in the Carter administration, on Mondale's campaigns and covered the two in the Minnesota and national press corps, packed into the ballroom, which had comfortable chairs on stage for the discussion between the two former leaders.

Carter, who flew to Washington from Atlanta where he is battling brain cancer, lauded Mondale as a "perfect partner," recalling their success in securing passage of the Panama Canal Treaty, rescuing  Southeast Asian refugees, and raising the importance of human rights as an element of U.S. foreign policy.

"I don't believe we  had a serious argument during the four years --  better than my relationship with my wife," Carter said to laughter from the crowd. "I never had a meeting with any foreign leader or with any member of Congress from which Fritz Mondale was excluded,"  Carter said during the informal discussion, moderated by Richard Moe, Mondale's former chief of staff.

Carter was energetic and animated and made no mention of his battle with brain cancer, which he announced in August along with a new treatment regimen.

The two indicated continued agreement Tuesday, with both men lauding diplomacy and the recent nuclear agreement with Iran.

Carter said his commitment to human rights came from his experience growing up in the segregated South, and he recalled his administration's work promoting human rights in the former Soviet Union and in Latin America. "The greatest oppression in the world right now is against women and girls," he said, citing the threat of sexual slavery and human trafficking, which is growing in the United States.

After the Carter-Mondale conversation, Vice President Biden took the podium describing himself as a latter-day beneficiary of the arrangement that Mondale and Carter worked out long ago, that included giving the vice president an office in the West Wing for the first time.

“You’ve both done me a great favor and you’ve done President Obama a great favor," Biden said. "You have both made this the most worthwhile job I have ever undertaken.” He presented himself as Obama's emissary and adviser. "President Obama and I have ideologically had no disagreement. I mean none. Zero," Biden said during a morning seminar led by Mondale at George Washington University.

The crowd at both events was buzzing about whether Biden would challenge former secretary of state Hillary Rodham Clinton for the presidential nomination.

Biden said at one point that while Obama had two great secretaries of state, when foreign
leaders spoke with him they knew he was speaking for Obama.

The Biden presidential buzz created some discomfort for Mondale who is close to Biden  but who has already endorsed Clinton's bid for the nomination. Biden did not directly discuss his presidential ambitions Tuesday but he offered hints of his interest, including laying out new details about his position on the decision to raid the compound housing Osama bin Laden in Pakistan. In addition, he emphasized his ability to work with leaders with differing political views, which many in the audience interpreted as a jab at Clinton. "I don't think my enemy is the Republican Party," he said.

In an interview earlier this week with The Washington Post, Mondale lamented what happened to bipartisanship in Washington, including those efforts that helped usher in historic accomplishments, such as the Panama Canal Treaty and post-Watergate restrictions on intelligence community excesses.

"The polarization, the paralysis, of the federal government is one of the saddest things I've seen," he said. "We're hurting ourselves. Our adversaries are gaining joy over it. I hope somehow we can find a way to restore civility. We're not there yet, not by a million miles, but we sure need it."

James Hohmann contributed to this report