Since leaving office, Gül has progressively become more publicly critical of Erdoğan and the democratic backsliding in Turkey. He was mooted as a potential joint opposition candidate in the 2018 Turkish presidential election, initially supported by the Republican People's Party (CHP) and the Felicity Party (SP). However, having failed to gain the support of the third major opposition party, namely the İYİ Party, Gül announced that he had taken his name out of consideration due to the lack of universal opposition backing. He has since been involved, though not officially, with the Democracy and Progress Party (DEVA) of fellow former AKP defector Ali Babacan.