Hillary Clinton runs with xxx as her VP candidate.
Hillary is elected president.
xxx has health issues late in the 1st term and resigns.
Hillary asks Bill to step in as VP for the short remaining term period.
Hillary is assassinated.
Bill Clinton becomes President again.
(Is the rule regarding a maximim of 2 terms for a President 2 consectutive terms, 2 terms regardless of the points in time, or ELECTED to 2 terms)