tenure might be a better word.
A term of office is the legal limit on the time someone can serve in a political position before re-election. In some countries, the terms for some offices can be indefinite, because elections can be called by parliament before the legal time limit of the term is expired.
However, since one person can be re-elected, and hold office for more than one term, I would use the plural form or say "term or terms of office"