Is the colon after "are" optional?

Last month, PKR’s Selangor menteri besar Datuk Seri Amiruddin Shari was previously quoted saying that the chief ministers and menteris besar of the six states that must hold elections this year have tentatively agreed to call these simultaneously in June.

The six states are: Selangor, Penang, Negeri Sembilan, Kedah, Kelantan and Terengganu.

Is the colon after "are" optional?

Thanks.