"Physically he’s not exactly looking strong. I wouldn’t say that he looks like a picture of health," the ex-POTUS, 77, sniped of the current commander-in-chief, 80.
His words sparked quite the reaction on social media, with Twitter users noting that Trump isn't in very good shape himself.
"He should really look in a mirror!" one person quipped, while another wrote, "Pretty sure that mechanical physics and gravity would prevent Trump from being able to do a single pushup."
"Maybe Joe should wear makeup, put lifts in his shoes & dye his hair?" joked a third, referring to things Trump allegedly does to try and improve his appearance.
"Trump probably shouldn't be talking about looking strong and picture of health," a fourth person noted. "Just saying."
Biden isn't the only opponent Trump has mocked for their appearance, as he also made a jab at Chris Christie's 2013 weight loss surgery.
"Vivek Ramaswamy is now beating [Ron DeSantis] DeSanctimonious. Christie dead as his stomach band," he rudely remarked on Thursday, July 20, via Truth Social. "'Aida' [Asa] Hutchinson a solid minus 1%. I’m up 44 points!!! MAKE AMERICA GREAT AGAIN."
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In turn, the former Governor of New Jersey, 60, has poked fun at Trump for his age.
"Talking of fighting, if you and Trump got in the ring — he loves his UFC and stuff like that, right — if you got in the octagon, you and him, who would win?" Piers Morgan asked Christie during a recent interview.
"Come on. Guy is 78-years-old," Christie scoffed, incorrectly upping his age by a year. "I’d kick his a**."