Sioufas has been a member of New Democracy's Central Committee since 1997; previously he was a member of the Central Committee from 1979 to 1985 and from 1994 to 1997.
Sioufas war seit 1997 Mitglied des Zentralkomitees der Partei Neue Demokratie, zuvor war er dies von 1979 bis 1985 und von 1994 bis 1997.