Keulen served in the provincial council of Limburg 1994–1995 but gave up the seat when he was elected to the Flemish Parliament in 1995. Keulen was re-elected in 1999 and 2004.
Keulen held a position on the Limburg provincial council from 1994 to 1995, but gave up that role when he was elected to the Flemish Parliament in 1995. He later regained his seat in 1999 and 2004.