staunchly conservative area; conservative stronghold
Used in political commentary to describe a region or district where conservative parties or candidates consistently win elections. The literal gloss 'kingdom of conservatism' is a figurative translation.
That prefecture has long been known as a conservative stronghold.
今回の選挙でも保守王国の地盤は揺るがなかった。
Even in this election, the conservative stronghold's base remained unshaken.