Prunk was born in the small settlement of Loka pri Zidanem Mostu (part of the municipality of Sevnica), in central Slovenia, which was then the German-occupied Slovenian Styria.

In 1976, he obtained his PhD with a thesis on Slovenian Christian Socialist movement 1918-1941, which was still a controversial topic at that time.

In 2005, he was appointed by the Foreign Minister Dimitrij Rupel, as president of the Slovene-Croatian Historical Commission,[2] formed by the Government of the two countries, to shed light on the history of the relations between them.

After the split with the party, he became very critical of the then Prime Minister Janez Janša, whom he accused of being a "liberal with an authoritative touch, who aspires at becoming a Slovenian Piłsudski".

[4] After the parliamentary elections of 2008, Prunk explained his disappointment with the Slovenian Democratic Party as a consequence of its neo-liberal turn.

In Prunk's opinion, the party turned its back to the ideals of welfare state held by its founding father Jože Pučnik.