To quote an old post of mine:
***
It's more complicated than that.
"in the pre‑Depression years, Italian‑American voters cast their ballots for the candidates of the party in power at the local level. « Little Italies » in Republican strongholds usually delivered large majorities for the GOP. For instance, on U. S. Secretary of Treasury Andrew Mellon’s turf in Pittsburgh (Murray), Republican presidential candidate Calvin Coolidge received 70.5 percent of the Italian‑American vote in 1924. Similarly, when Philadelphia’s Republican boss William Vare ran for the U.S. Senate two year later (Salter), he carried the local Italian‑American community by a 97.4 landslide (
Pennsylvania State Manual, 1925‑27).
"For the same reason, however, the cities where the Democratic party controlled most positions under the spoils system in the municipal administrations and operated effective machines produced Democratic pluralities among Italian Americans in the 1920s as well. Boston had been the seat of a powerful Democratic organization since the late XIXth century and the local « Little Italy » went Democratic even during the decade of the Republican hegemony at the national level that followed World War I, with the only exception of the 1920 backlash at Wilson’s foreign policy (Martellone,
Una Little Italy 495‑569 ; Blodgett). After carrying the Italian‑American community in East Boston with 53.7 percent of the vote and the « Little Italy » in the North End with 70.1 in 1920, the GOP received only 33.1 percent and 38.7 percent, respectively, in the contest for the White House four years later. In those two districts, therefore, both Smith and Roosevelt built up their 1928 and 1932 majorities among Italian‑American voters (respectively, 92.6 percent and 94.5 percent in East Boston and 94.5 percent and 93.2 percent in the North End) from Democratic John Davis’ 1924 pluralities...
"Political coercion of workers on the part of their employers, who usually sided with the GOP, added to machine politics and the « full dinner pail » slogan in causing Italian Americans’ pre‑Depression Republican allegiance. The John A. Roebling and Sons Inc. company, a wire‑manufacturing plant in Trenton, New Jersey, successfully drummed up the Italian‑American vote for the GOP in the 1920s by providing jobs for the members of the city’s « Little Italy » who participated in Republican activities and dismissing those who did not (Peroni 73‑74). Similarly, in the same decade, subservience to the partisan orientation of their employers led the Italian‑American workers of the Scovill Manufacturing Company, a metal industry in Waterbury, Connecticut, to register as Republican voters and to contribute to the election of the chairperson of their company to the state assembly on the ticket of the GOP (Fasce 236‑37)..."
https://transatlantica.revues.org/212?lang=en
In short, before Al Smith and FDR, the Italian American vote was not by any means solidly Democratic--and even in Democratic Boston, bitter resentment of Wilson's foreign policy led to a landslide Republican victory in Italian-American neighbothoods in 1920.
(People tend to forget that there were *Republican* urban machines in the pre-New Deal era. But they did exist; they dominated Pennsylvania and Rhode Island, and made Chicago a competitive city, where Bill Thompson with his unabashedly "wet" views on Prohibition, did very well with the Italian-American vote.)