When Berlusconi, who is seeking a third term as prime minister, hinted at giving immigrants a vote, the League's response was so furious that the idea was quickly dropped.
The 66-year-old League leader, Umberto Bossi, was minister for reforms under Berlusconi until suffering a stroke in 2004, and once advocated the use of gunships to ward off immigrants.
The League spearheaded the so-called Bossi-Fini law under the last Berlusconi government that imposed tougher penalties for illegal immigration; its performance in the election could determine the character of the new government.
Another Berlusconi ally, prospective finance minister Giulio Tremonti, quipped that the PD "prefers couscous" to local food.
In the northeast, where the PDL is confident of a strong lead, a recent poll in three provinces indicated that 40 percent of residents see immigrants as a threat to law and order.
Legally registered immigrants make up nearly 5 percent of Italy's 58 million people but the number of illegals is unknown.
"Immigration is an important issue here," said Verona pensioner Armando Ferrone.
To curb what they see as delinquent behaviour by illegal immigrants, some mayors have taken matters into their own hands.
"Illegal immigrants represent one-third of Italy's prison population. In the north, it is over two-thirds," said Verona mayor Flavio Tosi, from the Northern League.
In Verona, where foreigners make up 12 percent of the population, immigrants seeking publicly funded housing must meet certain income and health conditions, though Tosi said this was justified by European Union housing directives.
The mayor of the town of Citadella, in the Veneto region, issued rules stating that foreigners can apply for residency only if they have adequate incomes and housing provisions and are not deemed "socially dangerous".
This was branded discrimination by the national government, but has been adopted by 40 other Veneto town halls.
