Isamaaliit
In 2003, Taagepera agreed to serve for half a year as the founding chairman of a new political party, Res Publica, which won the general elections that year and lead the governing coalition under Prime Minister Juhan Parts until April 2005. Taagepera tried to hold the party more or less in the middle of the spectrum (Taagepera even suggested he was centre-left politician). In 2005, Taagepera resigned his Res Publica membership, frustrated with the party's leadership style and move to the right (refer to his essay, "Meteoric trajectory"). In April 2006, Res Publica decided to merge with the national-conservative Pro Patria Union party.