▁Day , ▁a ▁president ▁has ▁not ▁been ▁chosen ▁or ▁the ▁president - elect ▁does ▁not ▁qual ify ▁for ▁the ▁presiden cy , ▁the ▁vice ▁president - elect ▁acts ▁as ▁president ▁until ▁a ▁president ▁is ▁chosen ▁or ▁the ▁president - elect ▁qual ifies . ▁It ▁also ▁author izes ▁Congress ▁to ▁provide ▁for ▁instances ▁in ▁which ▁neither ▁a ▁president - elect ▁nor ▁a ▁vice ▁president - elect ▁have ▁qualified . ▁Act ing ▁on ▁this ▁authority , ▁Congress ▁incorpor ated ▁" fail ure ▁to ▁qual ify " ▁as ▁a ▁possible ▁condition ▁for ▁president ial ▁succession ▁into ▁the ▁President ial ▁Su cc ession ▁Act ▁of ▁ 1 9 4 7 . ▁ ▁Se ctions ▁ 3 ▁and ▁ 4 ▁of ▁the ▁Tw enty - fif th ▁Am end ment ▁provide ▁for ▁situations ▁in ▁which ▁the ▁president ▁is ▁tempor arily ▁or ▁in def initely ▁unable ▁to ▁dis charge ▁the ▁powers ▁and ▁duties ▁of ▁the ▁office . ▁ ▁History ▁ ▁Before ▁the ▁Tw enty - fif th ▁Am end ment ▁▁ ▁On ▁April ▁ 4 , ▁ 1 8 4 1 , ▁only ▁one ▁month ▁after ▁his ▁inaug uration , ▁William ▁Henry ▁Harrison ▁died . ▁He ▁was ▁the ▁first ▁U . S . ▁president ▁to ▁die ▁in ▁office . ▁After ward , ▁a ▁constitution al ▁crisis ▁en su ed ▁over ▁the ▁Constitution ' s ▁ambigu ous ▁president ial ▁succession ▁provision ▁( Art icle ▁II , ▁Section ▁ 1 , ▁Cla use ▁ 6 ). ▁ ▁Short ly ▁after ▁Harrison ' s ▁death , ▁his ▁Cab inet ▁met ▁and ▁decided