sessions, signs bills and sends them to the President for promulgation, signs and promulgates parliamentary acts (other than bills), organises staff work, etc. The chairman is also empowered to call special sessions of parliament, enact bills vetoed by the President when the Verkhovna Rada votes to overturn a veto by a two-thirds majority, and participate in meetings of the National Security and Defence Council. In circumstances where the post of President of Ukraine becomes vacant, the Chairman of the Rada becomes the acting head of state with limited authority. The chairman in duties of the President may dissolve parliament, appoint or submit for parliamentary approval candidates for key official posts, grant military ranks or state orders, and exercise the right of pardon. The Constitution and Ukrainian legislation contain no provision for presidential succession in cases where the posts of President and Chairman of the Rada are vacant simultaneously. Presidium The Presidium of the Verkhovna Rada is a collective name that was adapted for the chairman and his or her deputies out of tradition. Before the collapse of the Soviet Union, it was an official office that was elected at the first session of each convocation of the Supreme Soviet. Originally it consisted of a chairman, the chairman's two deputies, a secretary, and 19 additional members. Later compositions of the Presidium changed. The Presidium was regulated by Section 106 of the 1978 Constitution of the Ukrainian SSR, which empowered the Presidium with almost all of the Verkhovna Rada's powers wherever the latter was not in session, on the nominal condition that any decrees be laid at the next parliamentary session for approval. Since the adoption of the Ukrainian Constitution the institution has been discontinued, but the term is used for the leadership of parliament that includes the current chairman and his or her deputies and may include faction leaders. The first session of every newly elected parliament is headed by a temporary presidium that consists of six members of parliament according to Article 18 of the Regulations of the Verkhovna Rada. Ceremonial opening and the first session of new convocation One of the most important sessions of the parliament is the first session of each newly elected parliament. The preparation for the session is conducted by the Preparation deputy group with support from the Office of the Verkhovna Rada. The formation of the group out of the newly elected People's Deputies