I think this is basically right:
Nixon, it should be said, really took one for the team here.
No real politicians wanted to run a hopeless race, she stepped up, pushed Cuomo left on issues, shed light on the IDC situation and contributed meaningfully to their defeat.
Not bad work at all.
— Matthew Yglesias (@mattyglesias) September 14, 2018
Beating Cuomo was always a massive longshot, but he’s the kind of ambitious pol who needs to be (but can be) pressured from the left; a high-profile challenger was useful.
Pinning down Nixon’s influence is impossible and not really important, but the big story is indeed the smashing of the Pierre Laval Caucus in the state senate:
Years of anger at a group of Democratic state senators who had collaborated with Republicans boiled over on Thursday, as primary voters ousted nearly all of them in favor of challengers who had called them traitors and sham progressives.
The losses were a resounding upset for members of the Independent Democratic Conference, who outspent their challengers several times over, but also a sign that the impatient progressive fervor sweeping national politics had hobbled New York’s once-mighty Democratic machine, at least on a local level.
The most high-profile casualty was Senator Jeffrey D. Klein of the Bronx, the former head of the I.D.C. In that role, he was for years one of Albany’s most powerful players, sharing leadership of the chamber with his counterparts in the Republican conference and participating in the state’s secretive budget negotiations.
But on Thursday, he was defeated by Alessandra Biaggi, a lawyer and former aide to Gov. Andrew M. Cuomo, after a campaign in which Ms. Biaggi cornered Mr. Klein into spending nearly $2 million — more than 10 times what she spent — since January, an astonishing sum for a state legislative race. (Cynthia Nixon, in her bid against Mr. Cuomo, spent less.)
“If this doesn’t prove that political currency is people over money, I do not know what does,” Ms. Biaggi said at her victory party. “We have now cut the head of the I.D.C. snake.”
Mr. Klein did not appear at his watch party.
Also defeated were five other former I.D.C. members: Senator Tony Avella in Queens; Senator Jose Peralta in Queens; Senator Jesse Hamilton in Brooklyn; Senator Marisol Alcántara in Manhattan; and Senator David Valesky in Syracuse. The only former I.D.C. members to survive the primary were Senator Diane Savino, of Staten Island, and Senator David Carlucci, of Rockland County.
Cuomo’s support for the PLC would have been political death in a just universe, but just ejecting the membership and forcing Cuomo to deal with a senate actually controlled by Democrats is the next best thing.