It seems like every last one of the Japanese politicians are senior citizens.
この場合、次のように言えると思います。
ーAll the politicians in Japan are old.
「日本の政治家は年寄りばかりだ」
politicians で「政治家」
ーIt seems like every last one of the Japanese politicians are senior citizens.
「日本の政治家はみんな年寄りのようだ」＝「年寄りばかりだ」
senior citizens で「年寄り・高齢者」
ご参考まで！
カナダ 
