The development of an automatic oral presentation assessment system is important for the educational researchers to assess and train the communication ability of school leaders. In this work, we aim at enhancing the performance of the existing pre-service school principals' presentation scoring system by including lexical information as an additional modality. We propose to use latent n-grams distributed word representations and weighted counts of part-of-speech tag to derive features from the speech transcripts in the National Academy for Educational Research (NAER) oral presentation database. We carry out two different experiments: Exp I is a binary classification task between high versus low performing speech, and Exp II is a continuous scoring on the entire dataset. In Exp I, the proposed framework achieves a competitive accuracy of 0.79, and in Exp II, by fusing this text-based system to the existing audio-video based system, we obtain a spearman correlation of 0.641 (18.05% relative improvement). The two experiments demonstrate the modeling power of our proposed framework and signify the substantial complementary information in the lexical modality while assessing the quality of an oral presentation.