While he was a Republican congressman, Sheehan had nevertheless earned the respect of many Democrats. This gave him the potential to possibly earn votes in the general election of an overwhelmingly Democratic city. However, he ultimately was handed a landslide defeat from Daley.
^The Chicago Political Machine and Black-Ethnic Conflict and Accommodation Quintard Taylor Polish American Studies Vol. 29, No. 1/2 (Spring - Autumn, 1972), pp. 50 https://www.jstor.org/stable/20147848