Jeff Weaver was Bernie Sanders' campaign manager for the 2016 presidential election and served as president of Our Revolution until June 2017. His book, " How Bernie Won: Inside the Revolution That's Taking Back Our Country -- and Where We Go from Here ," was published by Thomas Dunne Books. The opinions expressed in this commentary are those of the author; view more opinion articles on CNN.

(CNN) Every wing of the Democratic Party is rightfully outraged at voter suppression and disenfranchisement. Onerous voter ID laws , voting roll purges , felon disenfranchisement and more exist, or are springing up in one "red" state after another, with only one real goal -- keeping poor and working people, young people, and disproportionately people of color from voting.

In the midst of the 2016 presidential primary campaign, the DNC and both the Clinton and Sanders campaigns put aside their differences to jointly sue the Republican administration of Arizona over its shocking "mismanagement" of the election there that effectively denied the vote to legions of people. Thank goodness those things don't happen in "blue" states. Right?

Shamefully, they do.

Nowhere is this truer than in the great and solidly blue state of New York. It is no accident that, as confirmed by Politifact , "New York consistently ranks as one of the worst voting turnout states in the nation." In the recent New York primary (which was only for federal offices -- more on that in a minute), Alexandria Ocasio-Cortez scored her surprise victory in the state's 14th Congressional District with voter turnout in that district of an abysmal 12% . Compare that with the City of Chicago and Cook County at roughly 30% ; California at over 37% ; Montana, 41% ; and Idaho at 30%, with the county showing the lowest turnout clocking in at 22% -- almost double the turnout of NY-14. What's the matter with New York?

One of the ways that New York slams the door in the face of voters is the one-two punch of its closed primaries and its draconian party switch rules. Here's how it works.

A minority of states, including New York, still cling to party rules that exclude so-called independent voters from participating in the major parties' primaries. While these primaries may have been a step forward decades ago, when they replaced an even more exclusionary nomination process, they are now locking out huge number of Democratic voters. What are the impact of these rules?

Today in New York, if you are not registered to vote at all, you can register and declare a party affiliation about one month before the primary. If you're registered as an independent, but are so inspired by a candidate like Alexandria Ocasio-Cortez that you want to switch your party registration to Democratic, you'd better be a good planner. To vote in New York's federal Democratic primary -- which was held on June 26, 2018 -- you would have had to have switched your party registration by October 13, 2017.

That's right. You had to switch your registration more than eight months before the primary.

And that's the same deadline for the state-level primary being held in September, meaning, again you had to switch registration some 11 months in advance.

In New York, independents -- those who haven't enrolled in a party -- are the second largest group after Democrats in terms of party registration. (Republicans are effectively the third party in New York.) Who are these independents? Many of them are reliably Democratic voters, donors, and volunteers on campaigns. They are disproportionately young. Nationally, some 44% of millennial voters are registering as independents rather than with a party, yet polls show this age group overwhelmingly self-identifies as Democratically-leaning. Among the millennial generation's independents, African Americans are the most likely to lean Democratic, followed by Latinos.

Why does the New York Democratic Party insist on locking them out of the primaries and creating a culture of non-participation?

The answer is simple. These closed primaries allow party bosses to exert control over the elections. That gets us to the issue of the split primary in New York, where state and federal primaries are being held on different days. As a senior Democratic National Committee official quipped to me the other day, there's no reason to separate the primaries other than to decrease voter turnout.

Purveyors of commercial products spend untold sums to develop product and brand loyalty among the millennial demographic while our party is pushing them away.

How much bigger would Alexandria Ocasio-Cortez's victory have been if young people of all races could have easily enrolled in the Democratic party and been eligible to vote in the primary? And how many more candidates like Alexandria Ocasio-Cortez could be elected? The machine knows the answer and so they suppress the vote. It is so obviously a tool of voter suppression that the national Democratic Unity reform commission - comprised of members picked by Clinton, Sanders and the DNC -- unanimously voted to authorize the DNC to sanction the New York Democratic Party.

Some inside the Democratic Party retort that only someone who signs up for the donkey-emblazoned membership card should be allowed to vote in the primaries even if it means young people and disproportionately young people of color are locked out. They ignore how strikingly similar this argument is to those Republicans use to justify onerous voter ID laws.

Incredibly, the fix is easy. There is no statutory change needed in New York to open up the Democratic primaries to independents. According to testimony from New York election officials, the New York Democratic Party can change the practice by simply asking that it be done. But just like red state disenfranchisers, machine politicians use voter suppression to stay in power. The same political cowardice that motivates Republicans who want a rigged election process motivates these antiquated rules in New York -- fear that in a fair fight the voters will choose someone else.

But the onerous registration process and split primaries are not the only tool of voter suppression and disenfranchisement that New York uses. The New York City Board of Elections, for instance, admitted that it illegally purged over 200,000 names from its voter rolls during litigation with the United States Justice Department and others.

Follow CNN Opinion Join us on Twitter and Facebook

The same is true of the embarrassingly early party switch deadline -- which is by far the longest in the country . There are policies designed by those who don't want to build and expand the Democratic Party but rather to control it and make it less responsive to its base and the needs of voters.

Voter suppression has a long and ugly history in America and Democrats of all stripes need to fight it. It is hard to credibly combat Republicans' despicable voter suppression efforts when millions are effectively denied the ballot in the Empire State. It's time to get our own house in order so we have the moral authority to protect the voting rights of people everywhere.

This article was updated to clarify that, among millennial independents, African Americans are the mostly likely to lean Democratic.