(S (S (PP (IN At) (NP (BASENP (DT a) (NN press) (NN conference)) (BASENP (NN yesterday)))) (COMMA ,) (S (BASENP (NNP Democratic) (NN candidate) (NNP Barack) (NNP Obama)) (VP (VBD doubted) (SBAR (IN that) (S (BASENP (DT a) (JJ potential) (NNP Nader) (NN candidacy)) (VP (MD would) (VP (VB have) (NP (BASENP (DT the) (JJ same) (NN impact)) (PP (IN as) (PP (IN in) (BASENP (NN 2000)))))))))))) (PERIOD .))