The Italians did the smart thing and joined the Yankees in the Republican party, which is what kept Mass a Republican state until the 1950s. Italians and Poles never had the chip on the shoulder towards those who founded this country like the Oi-Rish did. ;-)
The Irish in Boston had become a major political force in the late 1880s - well before the 1950s. The first Irish Mayor was elected in 1885. I have never heard about the Italians allying themselves with the Republicans ( read Yankee / Brahmins / Protestants). I can't imagine why they ever would. They were looked upon as a source of cheap labor by the Yanks and thats about it. The Italians were often pitted against the Irish as a source of cheap labor and both groups had more in common being poor and Catholic. I'm certain there were far more Italian Democrats than Italian Republicans. As for the Poles they were never here in Boston with the numbers like the Irish and Italians.
As for the Irish having a chip on the shoulder. During that time period, why shouldn't they? Sure, come to America after roughly 600 years of oppression and still be treated like garbage? Its no surpirse that after so many generations of living ' cap in hand ' for the English on Irish lands they were more than a little pissed off to face similar attitudes in their new land. The attitude of ' Dont take crap from anyone ' was one thats taught from generation to generation.
Years ago I had a crew of recent Irish arrivals walk off a moving job we were doing. Why? Because the idiot we were moving noticed they were Irish and said with a smile to me ' Irish ? All back and no brains eh? '
One of the crew spoke for all of them when he told me ' We left our country to escape that type of crap and you expect us to take it here too? '. Some things dont change.