President Joe Biden expressed concern for King Charles III on Monday after Buckingham Palace announced the monarch’s cancer diagnosis.

Speaking at a campaign event in Las Vegas with culinary union workers at the Vdara hotel ahead of Nevada’s presidential primary Tuesday, Biden said, “I’m concerned about him. Just heard about his diagnosis.” He said he hopes to speak with the king, “God willing.”

The palace announced in a statement earlier Monday that the 75-year-old British monarch has been advised by doctors to “postpone public-facing duties” while undergoing treatment.

The king spent three days in a London hospital for prostate treatment last month, during which doctors detected a form of cancer. The palace has not announced the type of cancer the king has.

The palace said Charles chose to disclose his diagnosis to “prevent speculation and in the hope it may assist public understanding for all those around the world who are affected by cancer.” It said that Charles, who became king in 2022 after Queen Elizabeth II’s death, looks forward to returning to “full public duty as soon as possible.”