I've posted a few items describing potential divisions with the Republican Party mostly because its unusual for the party to have them. The Democratic Party almost always has internal divisions. These reflect the diverse nature of the party.
But here's an argument that these divisions will increase during Obama's second term, since the leaders of each will begin positioning themselves for 2016. Might this undermine the party's ability to take advantage of the splits within the Republican Party? As always it will depend on whether some external force can be found that enforces party cohesion and convinces these factions to put individual goals aside.
That's always a tough order.