Simplify the following text for a Grade 9 native English-speaking person.
Original: Donald Franciszek Tusk ( born 22 April 1957 ) is a populist Polish politician , co-founder and chairman of the Civic Platform ( Platforma Obywatelska ) .
Simplified: Donald Tusk ( , born 22 April 1957 , GdaÅ sk ) is the Prime Minister of Poland ( from 2007 ) . He is also the leader of the biggest Polish political party , Platforma Obywatelska ( Civic Platform ) .