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Biden's son zings Ryan's marathon time

CHARLOTTE, N.C. -- Even top Obama campaign attack dog Joe Biden hadn't made this joke yet. 

It was Biden's son Beau -- the attorney general of Delaware as well as an active Obama campaign surrogate -- who today  took aim at his dad's rival Paul Ryan for amending his stated marathon time and suggesting that his athletic 61-year-old stepmother could beat the GOP fitness buff.

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"The Romney-Ryan budget means what it says," the younger Biden told an audience of veterans at a DNC gathering. "I believe his math as relates to his budget. I'm not sure if I believe his math as it relates to his marathon times." 

Zing.

Ryan has been criticized for boasting to a conservative radio host that he clocked in at "two hour and fifty something" during a 1990 marathon. His actual time was later revealed to be closer to four hours, a mistake Ryan has attributed to the decades gone by as well as to a back injury that prevented him from running later in life.

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Ribbing Ryan for mistaking the time -- "not something you forget, right?" -- he added that his stepmother Jill Biden ran the same distance in about four and a half hours. (According to the Marine Corps Marathon website, Dr. Biden completed the 1998 race in 4:30:02.) 

"So I guess he could compete with my mom," Biden concluded. "Maybe not, I think my mom can take him."