"9/11 Democrats"
However, I think that the change is even more basic. If I were to generalize, I see a huge philosophical devide. I see Republicans as having a faith that they can make a better life for themselves, if Government does not get in the way and yet they want Government to provide for certain basic securities like protection from foreign terrorism, keeping career criminals locked up, and some infrastructure things.
I see Democrats having a believe that the vast majority of Americans live life on the edge of disaster (job loss, illness, violent crime, big corporations that will outsource jobs-cheat people out of retirement-sell defective goods that kill or maim-steal folks money & run-overcharge for basic necessities-gouge people when they are down, being discriminated against by society.) This group looks to an all powerfull government to protect them and to "punish the other guy." This is why class warefare, minority, sexual orientation & ethnic rights, along with the trial lawyers lobby are so much a part of the Democratic party.
I see the 9/11 Democrats as being smart enough to realize that protecting against corporations is far less important that protecting against terrorists. They have seen the death and destruction that terrorists can do both in terms of people killed and injured and in terms of economic crisis. The 9/11 terrorists destroyed more travel industry jobs than any corporate outsourcing. The 9/11 terrorists killed more people than any "gun control" bill would have off set. The 9/11 terrorists created more air pollution than any environmental law that could have passed and not killed jobs.