In May, the Maine Democratic Party delivered a blow to the Democrats' decades-long practice of letting hundreds of party leaders and elected officials vote the way they want at the convention — though, of course, they have never overturned the will of Democratic primary voters.

The state's party decided to require its superdelegates, starting in 2020, to vote according to the primary and urged its 2016 superdelegates to do the same. Since then, several states followed Maine's example, and the Democratic National Committee agreed over the weekend to drastically cut back superdelegates' role in the party's nominating process altogether: Starting in 2020, two-thirds of the party's superdelegates will have to vote the way their state voted.

The Fix spoke to one of the leaders of this movement, Maine state Rep. Diane Russell (D), a Bernie Sanders supporter, throughout the primary season. We caught up with her while she was at the convention in Philadelphia. Our conversation is lightly edited for length and clarity.

THE FIX: When we talked back in April, you predicted this would be an issue at the national convention.

RUSSELL: [Laughs]. I keep using this as an example: I told The Washington Post that I was really hoping it would catch fire. I didn't think it actually would.

THE FIX: So what happened?

RUSSELL: We set up a commission that, as part of its job, addresses the issue of superdelegates. I don't normally like commissions, because it's basically: Let's study this so we can put it on the shelf, and people can go away. When I went into this, I was like "Absolutely no commission."

But the way this was negotiated was really well done. The commission members are told: "You will find two-thirds of the superdelegates, and you will eliminate them."

You've probably heard the term "superdelegates" recently – but what is a superdelegate, and why do they matter in this election? (Peter Stevenson/The Washington Post)

THE FIX: Is this a victory?

RUSSELL: Absolutely. Without a clarification.

We got a fair compromise that has real teeth to it and will deliver the structural change that will ensure going forward for generations to come that the way we nominate the president of the United States in our party is going to be fair, and party leaders will not be able to trump the rights of the voters.

THE FIX: Why not abolish all superdelegates?

RUSSELL: There are people who, in African American communities, for example, the superdelegates provide them an opportunity to counterbalance some of the power they have lost or don't have, because of problems like gerrymandering.

THE FIX: Hillary Clinton won this nomination with a big majority of superdelegates, yes, but she also won with more regular delegates and the popular vote. What do you say to critics who say that focusing on superdelegates is a waste of time?

RUSSELL: Ultimately, it comes down to elected leaders should not have the ability to trump the will of the popular vote. It didn't trump the will of the popular vote this time around. But it did tell us there's a risk of that happening.

There's a real fissure in the system that could backfire on us and came close to backfiring on us this time around. We need to fix that, because at the core, people need to have faith in their electoral system, and this calls that into question.

THE FIX: Outside of a few states, fixing the superdelegate system did not seem to be on Democrats' radar until now. How did you get the Democratic National Committee to overwhelmingly vote to get rid of most of them?

RUSSELL: We know that we have a DNC that's far more friendly to addressing this — we've had major discussions across the country about eliminating superdelegates, and more than 750,000 people signed a petition saying "Please abolish superdelegates outright." Also, I never dreamed in a million years getting it past the [Maine] convention would lead to this kind of snowball effect at other state conventions. [Editor's note: Alaska Democrats approved a resolution to force Democrats to end superdelegates. So did Vermont. So did Hawaii. There were stirrings that Wyoming and Oregon and other states were to do the same.]

So when we got to the negotiating room [at the convention], people were chanting "End superdelegates. End superdelegates."

THE FIX: So walk me through what will happen in the 2020 Democratic primary when superdelegates don't have nearly as much power.

Then the momentum gets put back where it should be — on the voters, and what they perceive to be the best candidate, and then you don't get that momentum. The momentum is supposed to be based on the vote that day, instead of based on the vote that day PLUS a handful of people in the state who can go either way and are not beholden to anyone other than their own conscience.

We were fighting for something that we really, really believe in. Without question, I know we are on the right side of history.