Aged 36, he was one of the LV's rising stars, alongside Luca Zaia, who was contextually appointed vice president and soon became his main rival within the party.

[3][4] However, in December 2009 Tosi had to renounce his bid to become President of Veneto in favour of Zaia, who commanded a larger support in the party's national council.

[12] In March 2015, after a long struggle with Zaia, backed by LN's federal secretary Matteo Salvini, was ejected from the party.

In 2022, Tosi ran again for a third term for the Mayor of Verona in an attempt to succeed his successor, Federico Sboarina, who had refused to include the center-right party Forza Italia in his coalition.

[18] In 2024, Tosi was included on the Forza Italia's European Parliament list in North East Italy.

[20] On 2 December 2004 Tosi was found guilty of instigation to racism according to the Mancino law, for having collected signatures against the establishment of new gypsy camps in Verona.

[21] In June 2008 the Court of Cassation publicized the motivations of its December 2007 sentence, stating that Tosi was not guilty of promoting ideas of racial superiority or hatred and that it is acceptable to discriminate against Roma on the grounds that they are thieves, indicating that the Court of Appeals should not consider as crime political initiatives aimed at illegal acts of minority members.

[22][23] On 20 October 2008 the Appeals' Court of Venice upheld the conviction of Tosi to two months of imprisonment with suspended sentence.