The incumbent is the current holder of a political office. To vote "non-incumbent" would mean to vote for the challenger to the incumbent's position.
An incumbent is an elected official who holds an office and is running for reelection.
incumbent
"incumbent' is the word you want. I think.
It is incumbent upon the government to deal with pressing environmental hazards. The social services agency enforces the care standards that are incumbent on foster parents. The challenger defeated the powerful incumbent to become the new governor.
The incumbent is demanding a recount.
The word "incumbent" is used to describe the candidate who is currently in office. Since Barack Obama is the president, he is thus called "the incumbent." This may change when the 2012 election is held, but as of today, he remains the incumbent, and his opponent is called the "challenger."
Re-Election
The correct term for a current officeholder who is running for re-election is "incumbent."
incumbent
Incumbent
incumbent