(S (S (BASENP (DT The) (NN by-election)) (VP (VBZ has) (VP (VBN been) (VP (VBN caused) (PP (IN by) (NP (NP (BASENP (JJ former) (NNP Prime) (NNP Minister) (NNP Helen) (NNP Clark) (POS 's)) (NN departure)) (SBAR (S (VP (TO to) (NP (VB head) (BASENP (DT the) (NNP United) (NNPS Nations) (NNP Development) (NNP Program)))))))))))) (PERIOD .))