President Obama has a "backbone like a ramrod."
https://talkingpointsmemo.com/livewire/biden-obama-has-a-backbone-like-a-ramrod
"They were good friends and Beau had great respect for Kamala, knew she was tough. She has a backbone like a ramrod."
https://www.msn.com/en-us/news/politics/biden-to-roberts-harris-had-the-best-recommendation-she-can-get-my-son-beau/ar-BB18hX91
"She has a backbone like a ramrod," Joe said.
https://nypost.com/2020/08/19/jill-biden-recalls-family-struggles-in-endorsement-of-husband-at-dnc/