Katie Porter opens door to presidential age limits in Senate debate

Candidates spar over whether Biden , 81 , and former President Trump , 77 , are too old to serve a second term in the White House .

Rep. Adam Schiff , 63 , defended Biden and used the question to pronounce Trump as unfit for office, at any age.

Republican Steve Garvey , 75 , cast the president in a pitiful light breaking with those in his party who sense political opportunity in mocking the president's mental acuity.