Simplify the following text for a Grade 11 native English-speaking person.
Original: Wulff was sworn in as Prime Minister on 2003 , as the head of a coalition between centre-right Christian Democrats and liberal Free Democrats ( FDP ) .
Simplified: Wulff was sworn in as Prime Minister on 4 March 2003 , as the head of a coalition between centre-right Christian Democrats and liberal Free Democrats ( FDP ) .