The new Iron Lady of politics - Michelle Obama

Politics has a new Iron Lady - after Michelle Obama knocked out 25 stunning press-ups on American television.

President Barack Obama's wife was being interviewed by Ellen DeGeneres and promoting her health agenda when the prime-time TV host challenged her.

DeGeneres, 54, asked the First Lady how many press-ups she could do and wondered if it was more than her.

Obama teased DeGeneres, "I know you've got these back issues," before DeGeneres rose to her feet and removed her jacket.

The First Lady embraced the competition, taking off her black leather jacket as the audience applauded.

The pair performed the repetitions together until they got to 20 when DeGeneres stopped, a little out of puff.

Looking unperturbed, Obama, 48, kept on, pressing out another five as the studio audience cheered her.

"That was amazing," said the host, soundly beaten.

- AAP