I also think that the Irish identity and history plays a big part of this. Here is Massachusetts practically everybody in politics has an Irish name, so there is the unholy trinity of being an Irish-Catholic-Democrat. You can't seem to separate them. Every Saint Patrick's day the politicians and the Catholic clergy go to the local halls and have a St. Patrick's day dinner complete with jokes, songs and stories. It seems like a big Irish love-in. It looks like the priests have been too close to the Irish Catholic political leaders for too long.
At one time, the Democrats did not have any ideology that went directly against the Catholic church but now the Dems are arrogantly challenging the authority of the Catholic Church in its own realm. Even the funeral of Ted Kennedy was used as an opportunity to politic and take digs at the Catholic teachings.
The Knights of Columbus was a strong Catholic mens organization but it now has been taken over by the Democrat liberal politicians. Politicians like to belong to every kind of organization because it gives them the opportunity to network and build a group of political supporters. Now the politicians in the Knights of Columbus are actively subverting the churches role as a moral voice in the making of laws.
It's pretty much the same throughout the northeast. The film Far and Away provides some insight into the world of Irish immigrants to the US. This "relationship" between immigrants and government has been passed down from one generation to another. They have failed to adjust their thinking to conform to church teaching.
Same thing is happening right now with Hispanics, except 10 times as bad.