 Despite the dissolution of the IDC, lawyer and first-time candidate Alessandra Biaggi challenged Klein in the 2018 Democratic Primary election.In September 2018, Biaggi defeated Klein by a nine-percent margin; his upset loss was attributed to long-simmering anger with the former members of the Independent Democratic Conference.Klein spent $2.4 million during the primary campaign, outspending Biaggi by a large margin.