It goes back a lot longer than that. I think that when Robert Bork got the reception he got from the Democrats then that really started it and it grew from there. Reagan begot Clinton which begot Bush which begot Obama. Now each side is using anything as an excuse to retaliate against the other.
Maybe I'm personalizing it too much, but I think the situation is now qualitatively different.
I know that I never felt such loathing and contempt for a president as I do for Obama. I didn't like many of Bill Clinton's policies, and I voted against him, but I still respected him as commander in chief. I could trust him to make an apolitical, wholesome speach to children.
I can't say the same for Obama. I simply do not trust him for a second. Everything he does seems to be calculated to advance his radical agenda, which I loath and which I believe might very well destroy the country I love.
My hunch is the same thing is true about GW Bush and people to the left of center. The loathing and contempt they had for him was unprecedented.