For most of the last century the south was a one party segment of the nation. Everyone in the South who could vote was a Democrat. The South was fiscally and socially conservative but every legal voter was a Democrat because of the race issue.
On fiscal and social issues, not including race, the Midwestern Republicans and the Southern Democrats were on the same page. They often cooperated in a "Bipartisan" manner. By the same token the North Eastern Republicans were very much like the industrial State Democrats. The Northeastern Republicans were Republicans because of the Democrat position agaist civil rights.
Once the Democrats under LBJ went strong for civil rights, people with similar political views outside of race moved to the same party.
The Southern Democrat became a Southern Republican and the Northern Eastern Republican became a Democrat.
For the first time our nation has nearly all conservatives in the Republican party and all Liberals are in the Democratic party. Soon the remainder of the liberal Republicans like Senaters Snowe and Chaffee will be gone. Soon the remainder of the Cconservative Democrats like Zell Miller will be gone.
The realignment makes what people think of as Bipartisanship impossible. There will very soon be NO Republicans that agree with Democrats on anything. And NO Democrats that agree with Republicans on anything.
As the two parties become even more polar opposites of each other, there will be a lot more fighting and a lot less getting along.
The Days when a Rayburn and Martin could share views on many issues are long gone. Even the days when an O'Neil and Reagan could work together for a tax cut are gone.
The party leaders and the rank and file are all of the same philosophy on both sides. That is a prescription for knock down drag out fights. It is not a prescription for bipartisanship.