Following his appointment as first deputy prime minister, many political observers began to regard Medvedev as a potential candidate for the 2008 presidential elections,[20] although Western observers widely believed Medvedev was too liberal and too pro-Western for Putin to endorse him as a candidate. Instead, Western observers expected the candidate to arise from the ranks of the so-called siloviki, security and military officials many of whom were appointed to high positions during Putin's presidency.[12] The silovik Sergei Ivanov and the administrator-specialist Viktor Zubkov were seen as the strongest candidates.[21] In opinion polls which asked Russians to pick their favourite successor to Putin from a list of candidates not containing Putin himself, Medvedev often came out first, beating Ivanov and Zubkov as well as the opposition candidates.[22] In November 2006, Medvedev's trust rating was 17%, more than double than that of Ivanov. Medvedev's popularity was probably boosted by his high-profile role in the National Priority Projects.[23]
Many observers were surprised when on 10 December 2007, President Putin introduced Medvedev as his preferred successor. This was staged on TV with four parties suggesting Medvedev's candidature to Putin, and Putin then giving his endorsement. The four pro-Kremlin parties were United Russia, Fair Russia, Agrarian Party of Russia and Civilian Power.[21] United Russia held its party congress on 17 December 2007 where by secret ballot of the delegates, Medvedev was officially endorsed as their candidate in the 2008 presidential election.[24] He formally registered his candidacy with the Central Election Commission on 20 December 2007 and said he would step down as chairman of Gazprom, since under the current laws, the president is not permitted to hold another post.[25] His registration was formally accepted as valid by the Russian Central Election Commission on 21 January 2008.[26] Describing his reasons for endorsing Medvedev, Putin said: