The word "incumbent" refers to the person who is currently in office. So, the incumbent president refers to President Obama. His challenger in the 2012 election was Mitt Romney. In politics, the incumbent is the one who holds the job-- whether it's the governor or mayor or president; the person trying to win that job in an election is the challenger, who is trying to defeat the incumbent.
Yes
NO-- Nobody can be forced to run for president or for any other elected office.
AS the US has only one president it must be whoever is the present incumbant.
President: James Madison Vice President: George Clinton
1980, when Jimmy Carter lost to Ronald Reagan.
Jimmy Carter
Yes
(Stephen) Grover Cleavland. As an incumbant president, he lost the 1888 election to Benjamin Harrison, but defeated Harrison in the 1892 election.
No it is not a clue at all
If an incumbent president is seeking a second term in office, his or her party is likely to nominate the president in question. In the U.S., presidents can serve two, 4-year terms.
lame duck
Incumbant