This study explores the role Chinese government in-house interpreters have played at several high-level annual press conferences hosted by the Chinese government. By analyzing their interpreting choices for elements of MOOD, defined in the Systemic Functional Linguistic as a discourse analysis tool and using data from a self-built corpus consisting of multiple video clips of the events, this study has discovered that the interpreters realise a level of interpersonal alignment with only one party in interpreter-mediated communication, and that the choices of alignment are heavily affected by the interpreter’s evaluation of the power relationship. The findings also suggest that although greatly constrained by their institutional roles, these interpreters remain as linguistic professionals. However, their grammatical choices demonstrate a tendency of their shifting social positions between the speaker and the addressees, betraying their deliberate efforts in embracing two roles in interpreting for the press conferences - one as inseparable part of the institution with allegiance pledged to the government, and the other as individual interpreters adhering to the norms of the profession.