RanchHand, the reason there was so much rancor with Bush is that Democrats feel, rightly or wrongly, that Bush stole the 2000 election. Gore got more votes than Bush; the recount in Florida was under way.
Then the Republican majority on Supreme Court ordered the recount stopped, effectively giving the election to another Republican, Bush. The vote was 5 to 4, All Republican justices voting one way, all Democratic justices voting the other.
The whole thing stunck to high heaven as far as Democrats were concerned. In his speech after SC decision, Gore did tell Democrats to forgive and forget and to move on. Again, to his credit, he was not bitter, he moved on, and went on to win the Nobel Prize. He probably came out ahead by losing the election.
The Democrats on the other hand, never forgave Bush for stealing the election. And this included Democratic voters as well, not just Democratic politicians. Also, Bush was not interested in bipartisanship. He, along with Carl Rowe decided to become the President of 50%+1 people from day one. Indeed, that was the strategy of Carl Rowe, divide and conquer. His strategy was to keep 50%+1 Americans happy and hang the rest.
And it worked; Bush won in 2004 by a narrow margin. So neither Bush nor the Democrats were interested in reaching across the isle. Whatever rancor was there, I think Bush was largely responsible for that, with his antics.
With Obama, it is different. He won the election convincingly, struck a bipartisan note right from the beginning, he kept some Bush appointees on, included some Republicans in his cabinet. So it is only the rabid right wingers who have a visceral hatred for him, the rest of the American electorate is willing to wait and see how he performs.
