In the 1960s there were still many conservative Democrats and probably no Republican senators from the South. Things have changed greatly since and George McGovern’s candidacy in 1972 opened the floodgates of conservative Democrats leaving for the Republican party, a process that was largely finished early during the Slick Willie years.
There are no longer any Democrats who stances on the issues align with JFK’s with the possible exception of Joe Manchin, or maybe some obscure members of Congress from some Western states.
“There are no longer any Democrats who stances on the issues align with JFK’s”
That is true.
If JFK were in politics today he would be considered a right wing Republican.