Former President Bill Clinton stops by David Letterman’s show tonight to wish him well as Letterman prepares to step down from CBS’ Late Show next week. President Obama and First Lady Michelle Obama paid their respects during the past couple of weeks to the longest-running late-night host in U.S. TV history.

“Put it in a percentage: What’s the chance of you moving back to 1600 Pennsylvania?” Letterman asked Clinton during the taping this afternoon.

“Well, first of all, Hillary has to win the nomination,” Clinton answered coyly. “If she wins the nomination, then she has to win the election. If she wins the election, the chances are 100% I’ll move back – if I’m asked. My experience, since I left the White House – when a president of either party asks, you say ‘yes.’ I hope I’d be invited. … It would be a good thing for America if she won. I hope she does.”

“What an amazing life this has been and could continue to be for both of you,” Letterman marveled, or deadpanned — hard to tell.

Since they had their first grandchild, Clinton explained, he and Hillary try to “wake up every day in a good humor and be grateful. … We’ve had a wonderful life.”

Letterman noted they had discussed how it’s sometimes easier for someone to be more effective out of office than in. “You’re about to find out,” Clinton joked.

“My god – I take that as a challenge” Letterman responded. “You’re exactly right!”

Earlier in the day, Clinton stopped by Univision’s upfront presentation, to preach the benefits of diversity and “radical inclusion” during a 15-minute interview with Alicia Menendez, an anchor at Fusion, the company’s joint venture with ABC.