The populist 5-Star Movement and the right-wing League both signaled support for a Draghi-led government, saying they were ready to put aside bitter rivalries in the national interest.
The €6.99 paperback was first released in February 2019 but made it top of the Amazon bestseller list in Italy on December 4.
Salvini is accused of abusing his powers as then-interior minister to block 116 migrants from disembarking from a coastguard boat last year, under his so-called "closed ports" policy.
The anti-government rally was joined by League's allies Brothers of Italy and Forza Italia.
Sunday could see fatal cracks appear in Italy’s coalition government. Here’s how.
Members of 5-Star will hold a ballot on the party's internet platform on Tuesday to decide whether the group should join forces with the Democratic Party, its traditional foe.