As the country's 39-year old Prime Minister Matteo Renzi and his centre-left Democratic Party (PD) battle to comply with European budget rules, Salvini, 41, is wooing recession-weary voters on an anti-immigration, anti-euro and overtly anti-Muslim platform.
"We want to have the majority in Italy. We are preparing for the future," the media-friendly former journalist said in a recent interview.
Giovanni Orsina, a professor of political science at the Luiss University in Rome, said Salvini is on track to emerge as a major player in the country's political landscape.
"He has the political space to do it," Orsina said, arguing that the Northern League is well-placed to surf a Europe-wide trend reflected most notably in the advances of Marine Le Pen's National Front in France.
Salvini is a self-confessed fan of Le Pen, who has softened the hard-right image of her party and broadened its appeal as voters across Europe have turned to populist parties in a backlash against Brussels and the economic gloom engulfing much of the eurozone.
Meanwhile, former premier Berlusconi's centre-right Forza Italia (FI) party is lagging seriously in the polls, but the media magnate has failed to find a credible successor.
"Silvio Berlusconi is in a very fragile position and he is an old leader, nearly 80 years old, compared to the young Salvini," Orsini said.
Salvini's aim is to extend the League's influence and appeal from the wealthy north of the country to the much poorer south, from where media tycoon Berlusconi traditionally drew much of his support.
He wants the party's "charter of values" to form the basis of a new movement which would appeal to all those who feel left behind by Renzi's reform drive or betrayed by his willingness to negotiate with Brussels over the country's debt burden.
'Decisive no to Europe'
According to Salvini, the values of his party include saying "no to immigration, no to mosques and yes to a drastic reduction in taxes."
He also advocates a "decisive no" to what he sees as the left-wing European Union.
"We have to take back our national sovereignty and currency," he said.
Earlier this week, Salvini told Israeli newspaper Haaretz that Islam was "the only religion that creates problems, in Italy, Europe and in the Middle East.
"If Muslims are having a hard time coexisting with the rest of the world, the problem cannot be with all the rest of the world. It must be Islam, and indeed the Koran itself is problematic."
Orsini said how far Salvini can go would depend on the League's ability to win votes in the south by switching the focus from Italy's north-south division to a common enemy in Brussels.
Antonio Noto, head of the IPR Marketing polling institute, is sceptical about that happening. The league's voters "are all still in the north, where they are scoring up to 30 percent, but there are no signs of growth in the south," he said.
Tarnished by fraud scandals in 2012, the League only received 4.0 percent of the vote in Italy's national election in February last year, rising to 6.2 percent in the European elections.
Voter intention polls currently rank it fourth with around 8.0 percent, behind Renzi's PD (40 percent), the anti-establishment Five Star movement (20 percent) and Berlusconi's Forza Italia (15 percent).
But the bearded Salvini is the second most popular of the party leaders, with 28 percent of people in a recent poll saying he inspired the most confidence – behind Renzi (54 percent), but ahead of Berlusconi (24 percent) and Five Star founder Beppe Grillo (19 percent).
While his success weakens the already depleted billionaire Berlusconi, political watchers say he is unlikely to be able to unite those on the centre-right with the far-right to form a credible challenge to Renzi's centre-left.
"Even if by some miracle the League won 20 percent of the votes, it would still be condemned to stay in the opposition because the split in the right would be too profound" to create a coalition, Orsina said.