Party politics in the US has always been ugly. The hypocritical pretense that it’s only the other side who’s to blame is not quite as traditional: it seems to have originated with the modern ideological Left.
Ugly party politics took a sharp turn for the worse in 2000 when Bush defeated Gore. The Demonrats felt that they were robbed, and whatever they do is OK as long as it helps to defeat the enemy which is everyone with an R behind their name. The level of hatred and vitriol displayed by the left today surpasses anything in my memory, and that memory began in the Eisenhower era.