Credit: Steinberg/Adao/

Secretary of State Hillary Clinton is hard at work helping her daughter Chelsea plan her wedding to investment banker Marc Mezvinsky.

"They're having a good time doing it," former President Bill Clinton said on Ryan Seacrest's KIIS-FM radio show Monday morning.

25 Pics! See stars' gorgeous wedding photos

His job?

"I'm just supposed to walk her down the aisle and pay the bills," Bill, 63, joked to Seacrest.

Chelsea, 29, announced her engagement to Mezvinsky, 31, last November.

Said her dad, "I must say I am very happy. My daughter is happy. I like and admire my future son-in-law, so I couldn't be happier about it."

The former president admits he'll "probably" tear up on his daughter's big day.

"I always thought being her father was my most important job, so it's a big day for me. It is the biggest day in her life, probably, and I'm happy," he gushed.