If it were 20 years ago, I think that he would not have had to resign
I think that if it were 20 years ago, he would not have resigned. People would have just thought, "oh a politician said something stupid again, we can't do anything about it, oh well," and it would have ended there.
20年前だったら、彼が辞任することはなかったと思う
I think that if it were 20 years ago, he would not have resigned. (have resigned=辞任した)
If it were 20 years ago, I think that he would not have had to resign (have had to resign=圧迫されて基本的に彼が辞任しないといけなかった)
どちらでも使って良いです。
なぜなら、政治家がまた馬鹿なこと言っているよ、でも、どうしようもない、しかたないね」で終わっていたと思うからです。
Because I think that people would have just thought, "oh a politician said something stupid again, we can't do anything about it, oh well," and it would have ended there.
ご参考になれば幸いです。
If this had happened 20 years ago, I don’t think he would have resigned.
**If this had happened 20 years ago, I don’t think he would have resigned.**
**Back then, people would've just said, "That's just another stupid thing a politician said" and let it go.**
「辞任することはなかった」は、実際には辞任したことに対して逆のことを述べているので、**wouldn't have resigned** が自然です。
また、「〜で終わっていたと思う」部分には **let it go**（流す、放置する）、**shrug it off**（軽く受け流す）、**brush it aside**（問題視しない）などが使えます。
アメリカ合衆国 
