President of Argentina
Under the 1994 constitutional amendment, the President serves for four years, with a possibility of immediate reelection for one more term. However, unlike the President of the United States, in Argentina, a person may be reelected again after serving for two terms and staying out of office for the following term. So after serving for two consecutive periods, the president is not allowed to run for a third consecutive one, but may return for the two following elections and so on. There is no limit for a person to be a candidate if he or she does not win the elections.
Acting President of the United States
An Acting President of the United States is an individual who legitimately exercises the powers and duties of the office of President of the United States even though that person does not hold the office in their own right. There is an established order in which officials of the United States federal government may be called upon to take on presidential responsibilities if the incumbent president becomes incapacitated, dies, resigns, is removed from office (by impeachment by the House of Representatives and subsequent conviction by the Senate) during their four-year term of office; or if a president-elect has not been chosen before Inauguration Day or has failed to qualify by that date.