"Personnel" is a group of people working for the same organization or company: http://www.merriam-webster.com/dictionary/personnel
Povo is a people, one people. The general coletive for people, normally referring to the inhabitants of a city/country. It's probably the best choice when talking about politics.
Pessoal is a group of persons, it can be my group of friends, it can be the staff of a company. O pessoal is a delimited group of people.