 Mantica was elected to the Senate of the 10th Legislature on the Movimento Sociale Italiano-Destra Nazionale (Italian Social Movement–National Right) Party ticket in 1987 in the Milan 3 constituency.Re-elected to the Senate of the 13th Legislature on 21 April 1996 in the Lombardy 14 constituency (Monza).Re-elected to the Senate of the 14th Legislature on 13 May 2001 in the Lombardy 14 constituency (Monza).