In 2018 the Working Families Party of New York targeted members of the Independent Democratic Conference for destruction. The IDC was a group of Democratic state senators who rejected their party's legislative leadership and formed a coalition with the Republicans, giving the latter leadership of the Senate. The IDC had disbanded by primary season, but eight of its members remained in the upper house. The WFP endorsed primary challengers to all of them, and took credit when six of them lost. As a result, some Democrats now apparently feel that the WFP has grown too powerful, or so a coalition of liberal lobby groups are warning. They hope to preempt an attempt to end the practice of fusion voting, which allows candidates to receive endorsements from multiple parties and appear on multiple lines in the general election ballot.
Fusion voting allows small parties like the WFP to have some leverage when trying to steer the two major parties in more ideological directions. By endorsing Democratic gubernatorial candidates, Working Families gets enough votes to maintain its line on the state ballot. That allows them to threaten to run truly independent candidates if the Democratic establishment fails to meet their demands. Practice doesn't always live up to theory -- in the gubernatorial election before last, Andrew Cuomo called the WFP's bluff and got them to endorse him meekly without any extreme concessions -- but the risk of getting primaried has only grown greater for incumbents of both major parties since then. Without fusion voting, Working Families could still run someone to take progressive votes from a Democratic candidate, but the WFP's allies clearly fear that the first time they did so they'd lose their ballot line.
The party's supporters claim that it has "helped Democrats win tough general election races up and down the ballot," but proof of that may be hard to come by. Working Families is self-evidently less an independent party than a pressure group within the Democratic party. It can't be a decisive force in Democratic primaries, after all, if its base didn't consist of registered Democrats. That fact makes the WFP a charade rather than "a vital piece of Progressive organizational infrastructure in New York and the nation," as its friends claim. It's anyone's right to demand more progressive (or more conservative, or more radical, etc.) candidates, but it isn't necessarily anyone's right to exploit another party's popularity in order to threaten it. I can understand that politicians outside the establishment want shortcuts to influence and power; the WFP favors fusion voting for the same reason Donald Trump runs as a Republican. But if the entrenched power of the two major parties -- sadly a cultural as well as a political fact -- remains the real problem, schemes like fusion voting don't get to the heart of it. They're cosmetic only, offering only a facade of progress when more radical reform may be necessary. If the American political system makes more radical change impossible, insisting that you can't do away with the major parties' electoral advantages until you beat them in an election, maybe fusion voting and the ballot access it allows are understandable. Just the same, don't expect people to cry for you should you be forced, after boasting of your strength, to stand on your own two feet and prove how strong you really are.