Former President Bill Clinton
Of the eight living past presidents and vice presidents, former President Bill Clinton is the only one who will attend either the Democratic or Republican convention in person.
While he hasn't always been in lock step with President Obama, Clinton will endorse Mr. Obama's re-election this September at the Democratic National Convention in Charlotte. Mr. Clinton will speak on Wednesday night during the convention, in the slot traditionally reserved for the vice presidential nominee.
Here's a look at what the other past presidents and vice presidents are doing: