The incumbent is still the president, and the new one is the president elect.
lame duck
George HW Bush
lame duck
"Sitting duck president" is a colloquial term that refers to a president who is perceived as being unprotected or vulnerable to attack or criticism. It suggests that the president is in a precarious position and easily targeted by adversaries or challenges.
It is called "lame duck"
He is a lame duck.
The period between election day (November 4th) and the inauguration of the next president (January 21st). The sitting-president is considered a "lame duck" since the president-elect will be strolling into the oval office within a couple of months.
It is called a "Lame Duck."
A president about to leave office is referred to as a "Lame Duck" president.
The usual term is a "lame duck" president, although this can also be applied to a two term president who's party is voted out of office for the next election - i.e. George H.W. Bush was a "lame duck" president because he only served one term, and George W. Bush was a "lame duck " president because his party lost the next presidential election.
Answerlame duck