Complex sentence: The cession of Kuala Lumpur had the effect of securing the Selangor state government for the Barisan Nasional until the 2008 general election, on which both the voters in Kuala Lumpur and other parts of Selangor tend to vote for the opposition.
Split into simpler sentences: The cession of Kuala Lumpur had the effect of securing the Selangor state government for the Barisan Nasional until the 2008 general election. This is because both the voters in Kuala Lumpur and other parts of Selangor tend to vote for the opposition.