2004 Belarusian constitutional referendum
A referendum on allowing President Lukashenko to stand in further elections was held in Belarus on 17 October 2004, alongside parliamentary elections. Lukashenko was nearing the end of his constitutionally-limited two terms, and the change would allow him to run for a third term.
Source: Wikipedia — 2004 Belarusian constitutional referendum (CC BY-SA 4.0)