In 1984 elections, he challenged Andrew Rogers, his former high school fellow for state representative seat and won.[6] In 1992, he was elected to the Massachusetts State Senate.[7] After eight years in the House of Representatives and twelve years in the Senate, he retired in 2004 and did not run for re-election.[4]
Magnani served on the Senate education committee and opposed Mitt Romney's proposal to reorganize the University of Massachusetts as part of his plan to cut the state's huge budget deficit in 2003.[8]
In March 2004, he and Representative David Linsky opposed the "Compromise Amendment," supported by House Speaker Thomas Finneran and Senate President Robert Travaglini, it aimed to prohibit gay marriage in Massachusetts, advocating civil unions with similar legal aspects.[9] Magnani frequently voted against amending the state constitution to prohibit same sex marriage in Massachusetts.[10]
In 2007, he was named as executive director of Massachusetts Nonprofit Network, an association of 25000 charities.[11]