The Democratic National Committee voted on Saturday to significantly curtail the power of superdelegates and make presidential caucuses more accessible.

The reform package, pushed by DNC Chairman Tom Perez and allies of Vermont Sen. Bernie Sanders, among others, passed overwhelmingly despite objections from a vocal minority of its membership at the DNC’s summer meeting two years after the process started.

“Today is a historic day for our party. We passed major reforms that will not only put our next presidential nominee in the strongest position possible, but will help us elect Democrats up and down the ballot, across the country.” said Perez.

The change will prohibit superdelegates from voting for president at the party’s 2020 convention, unless the outcome is already assured or it deadlocks, which hasn’t happened in decades. The vast majority of superdelegates sided with Hillary Clinton over Sanders in their primary fight two years ago.

The new rules will also make caucuses more accessible by requiring state parties to accept absentee votes, addressing concerns that the caucuses are less democratic than primaries because they require people to physically attend the events in order to participate in the presidential nominating process in their state.

Critics of the new reforms argued that it would disenfranchise party leaders and create tension between Democratic lawmakers and their constituents while others argued it gave Sanders, a self-described democratic socialist, undue influence over the DNC.