There is a 90% chance the new Prime Minister will be 〇〇.
There is about a 90% probability that 〇〇 will be elected as the next Prime Minister.
ーThere is a 90% chance the new Prime Minister will be 〇〇.
「90%の確率で次の総理大臣は〇〇になるね。」
a 90% chance で「90%の確率」
Prime Minister で「総理大臣:首相」
ーThere is about a 90% probability that 〇〇 will be elected as the next Prime Minister.
「約90%の確率で〇〇さんが次の首相に選ばれるね。」
a 90% probability でも「90%の確率」と言えます。
will be elected as ... で「…に選ばれるでしょう」
ご参考まで!