In recent months he has frequently referenced the trial and the forthcoming verdict in social media posts and during public speeches and interviews.
"I want to believe that Italy is a normal country, and in a normal country someone who defends borders isn't found guilty," he told Italian media earlier this week. If that was the case, he said, "it would be terrible news for the country and a reason to celebrate for people smugglers and enemies of Italy".
He has also alleged that the Italian judiciary was "politicised" and that some magistrates were "clearly following left-wing politics".
Elly Schlein, leader of the centre-left opposition Democratic Party, accused Salvini of "spreading propaganda and fuelling a serious institutional clash".
The three female prosecutors in the case have been under police protection since September after being harassed online and receiving threats.
Members of Salvini's Lega party have rallied around him and are preparing demonstrations in his support.
On Wednesday, Lega MEPs turned up at a European Parliament session in Strasbourg wearing t-shirts that read "Guilty of defending Italy" - a slogan Salvini has used in the past.
"A conviction would be an incredibly serious matter," said Lega deputy secretary Andrea Crippa: "It would be like convicting the entire Italian people, the Italian parliament and the elected government."
Lombardy's Lega party president, Attilio Fontana, said a guilty verdict would be "so aberrant, even from a judicial point of view, that I don't even want to think about it".
Others outside Italy have waded into the debate too.
"That mad prosecutor should be the one who goes to prison for six years," Elon Musk tweeted, while Hungarian Prime Minister Viktor Orban, a close ally of Salvini, called the trial "shameful".
If convicted, Salvini has said he will appeal against the verdict "all the way to the Supreme Court of Cassation" – Italy's highest court.
That process could take months and Salvini's position in the government and parliament would be unaffected.