Partly due to its obstruction of the regional budget, the IULV-CA vote share declined in 2000, following which Valderas lost his seat but became the group's new general coordinator. He ran for regional president in 2004, but was unable to even recover his seat in the Huelva constituency. He returned to parliament after the 2008 election.[2]
In the 2012 election, the PSOE of president José Antonio Griñán declined while the IULV-CA rose from six seats to twelve. The two parties formed a coalition government, with Griñán as president and Valderas as vice president and Minister of Local Administration and Institutional Relations. He became the first member of his party to hold the office.[3] He retained his positions in the new government when Susana Díaz took the Socialist leadership in 2013, while Antonio Maíllo succeeded him as party leader.[4]
In January 2015, after the PSOE and IULV-CA announced that they would no longer work together following March's elections, Valderas said that he would not stand in the election though he was not retiring. At 62, he decided to spend more time with his family and let the younger generation advance in politics.[5][6]
^Tortosa, María Dolores (30 January 2015). "Diego Valderas deja la política andaluza" [Diego Valderas leaves Andalusian politics]. Ideal (in Spanish). Retrieved 25 June 2022.