In January 1306, the citizens of Genoa replaced their Podesta with two Capitani del Popolo ("Captains of the People") as rulers of the republic, part of a constitutional struggle lasting from 1257 to 1339.
Spinola's co-Captain Bernabo Doria was the father-in-law of Manfred IV, Marquess of Saluzzo, who claimed some of the territory of Montferrat.
In 1310, Spinola managed to get himself appointed the sole Captain of the People for life.
However, his growing power made enemies, including even some of his Spinola kinsmen.
In late 1310, he was forced from office; in 1311 the Podesta was restored, and Spinola was placed under perpetual banishment from Genoa.