Original sentence: In addition, perceptions of pressure from the US, the EU, the United Nations and by a great part of the Greek political opposition, namely the PASOK party and its leader George Papandreou essentially backfired on those who made them, ending up in shifting to weight towards a "No" vote in the South
Edited sentence: In addition, perceptions of pressure from the US, the EU, the United Nations and by a great part of the Greek political opposition, namely the PASOK party and its leader George Papandreou, also had a negative effect in the South