Parliamentary election map
When Musk argues people in the annexed regions want to be part of Russia, he relies on the 2012 Parliamentary elections map when the Party of Regions was at its height of popularity. Furthermore he mistakes a pro-Russian party for a pro-annexation party. The influence of the Party of Regions significantly faded after the 2014 Russian war in the Donbas and the annexation of Crimea.
Its eventual successor party the Opposition Bloc would also have smaller significance in Ukrainian politics capturing only 9% of the vote in the 2014 parliamentary elections and only 27 seats in the Rada. Support would be primarily confined to Kharkiv oblast and the unoccupied regions of the Donbas.
The Opposition Bloc would eventually split into two parties the Opposition Platform-For Life and the remaining members of the Opposition Bloc. In the 2019 parliamentary elections the Opposition Platform-For Life would get 13% of the vote and 43 seats, far fewer than Zelensky's party Servant of the People. The Opposition Bloc would only get 3% and 6 seats. At this point support would be largely confined to the unoccupied regions of the Donbas.
When Russia invaded in 2022, the Opposition Platform-For Life demanded Russia withdraw all its forces from Ukraine and expelled members that supported the invasion.
Opposition Platform-For Life