Twenty-second Amendment to the United States Constitution
The amendment prohibits any individual who has been elected president twice from being elected again. Under the amendment, an individual who fills an unexpired presidential term lasting greater than two years is also prohibited from winning election as president more than once. Scholars debate whether the amendment prohibits affected individuals from succeeding to the presidency under any circumstances or whether it only applies to presidential elections.
President of the United States
Presidents may use their predecessors as emissaries to deliver private messages to other nations or as official representatives of the United States to state funerals and other important foreign events. Richard Nixon made multiple foreign trips to countries including China and Russia and was lauded as an elder statesman. Jimmy Carter has become a global human rights campaigner, international arbiter, and election monitor, as well as a recipient of the Nobel Peace Prize. Bill Clinton has also worked as an informal ambassador, most recently in the negotiations that led to the release of two American journalists, Laura Ling and Euna Lee, from North Korea. Clinton has also been active politically since his presidential term ended, working with his wife Hillary on her 2008 and 2016 presidential bids and President Obama on his 2012 reelection campaign.