Sen. Bernie Sanders (I-Vt.) speaks at a Nov. 1 rally against the Republican tax plan. (Chip Somodevilla/Getty Images)

Sen. Bernie Sanders, who declined to engage in the fracas over former Democratic National Committee chair Donna Brazile’s new tell-all book, is pushing for the DNC to adopt at least four changes to its primary process or risk losing credibility with progressive voters.

“Do you believe in open primaries, or do you not?” Sanders (I-Vt.) said in an interview in his Senate office. “Do you believe in transparency or not? Do you believe in keeping 700-plus superdelegates or not? Do you believe in letting people vote in caucuses who currently cannot? Those are the issues. There are some people thinking politically, giving all kinds of reasons [why not] — but those are the issues.”

The focus of Sanders’s mini-campaign is on the DNC’s Unity Reform Commission, created after the 2016 primaries — but before Hillary Clinton’s surprise defeat in the general election — to ease tensions among supporters of the two candidates.

On Dec. 8 and 9, the commission will meet for the last time and present recommendations to the full DNC. Sanders’s goal is twofold: To highlight the changes he wants most and to prevent the issue from fading when the full DNC meets again.

“This will invigorate the party,” Sanders said. “How are you a serious national party when in half the states, there’s no serious Democratic presence?”

Sanders’s DNC priorities have not changed much since the summer of 2016, when he began attacking the presence of “superdelegates” — unbound delegates to the party’s convention, whose number has increased every cycle — for giving Clinton an insurmountable lead.

Clinton ended up defeating Sanders in most primaries and would have secured the nomination had superdelegates not existed. But the bitterness surrounding the primary has endured. The release of Brazile’s book “Hacks,” in which she revealed a joint fundraising agreement favorable to the Clinton campaign ahead of the general election, introduced a whole new reason for Democrats to squabble.

Sanders, who has monitored the Unity Reform Commission’s work, argued that its recommendations should include new budget transparency, ending the mystery, for state Democratic activists, about where their money is going and where it might be used to help candidates.

“What is the process by which that money is allocated? We don’t know,” Sanders said. “We don’t have transparency. This is tough stuff, but it means to say that you can’t have a few people in meeting saying: Well, we can’t support the guy in Kansas. We can’t support the guy in Montana, or whatever. That process has to be much more open.”

In the interview, and in an article published Thursday by his grass-roots organization Our Revolution, Sanders did not specify how transparent the DNC needed to be. On the unity commission, Sanders-appointed members have argued for at least DNC members to get access to the budget, a request that became more popular after the release of Brazile’s book.

Sanders was more specific about his other favored measures.

One: He favors “dramatically reducing the number of superdelegates,” though not abolishing them. On the unity commission, ideas for reducing that number include eliminating delegate status for DNC members (while leaving it for elected members of Congress and governors) and allowing delegates to vote if they reflected the results of primaries.

Two: Sanders argued for Democrats to open all of their primaries, to whatever extent possible. That’s been a tricky issue for the unity commission, which spent its fourth meeting, in Las Vegas, listening to ideas for how states with strict registration rules could be forced to change if the party acted. The worst offender, Sanders said, was New York, where he discovered that voters who had not registered as Democrats before October 2015 could not vote in April 2016.

“We need to declare, as a party, that structures like the one in New York are unacceptable,” Nina Turner, the president of Sanders’s Our Revolution group, said at the commission meeting last month. “I can’t tell you how many times Republicans threw New York up in my face when I talked about voter suppression.”

“It’s a total incumbent protection process,” Sanders said.

Three: Sanders, who won all but one of the 2016 race’s caucuses, called for them to be opened up to people who could not physically attend.

“I like caucuses,” he said. “I like them because I like democracy. I like town halls in Vermont. But the pitfall comes if there’s a Saturday night caucus, you have a job or you can’t leave the house. We’ve got to make it so people who can’t attend can vote.”

Over the week, while he avoided embroiling himself in the Brazile story, Sanders ramped up his campaign for the new DNC measures. He circulated some of them in an email to supporters — “we got 60,000 signatures” — before posting Thursday’s piece. At the same time, he studiously avoided the Brazile topic, saying Wednesday night on CNN that Brazile “showed an enormous amount of courage in describing the truth as she saw it” but refusing to call the primary “rigged.”

“Our job is to go forward, is do everything we can to defeat this right-wing agenda of the Republican Party in the Trump administration, not to look backward,” Sanders said.

In his interview with The Washington Post, Sanders went further, saying that the Brazile story could not become a distraction from the DNC plan.

“The media likes all the divisiveness, and Clinton versus Sanders — fine,” Sanders said. “If Democrats are going to be sincere in taking on voter suppression, and making primaries open, allowing same-day party registration — this is what they need to do. You cannot continue to allow 25 states in this country to have virtually no Democratic Party at all. [It is] insane.”

Sanders, an independent with no plans to join the Democratic Party, has faced criticism by continuing to demand changes in the DNC — while being questioned by progressives who want him to build a third party.

At moments during her own book tour, Clinton has reminded interviews that Sanders was “not a Democrat” when he ran for president. Before Tuesday’s election in Virginia, Sanders was criticized by columnist Eleanor Clift for not stumping for Democrat Ralph Northam in the governor’s race.

“I was not asked to,” Sanders said. “I was asked to go to New York for de Blasio. I was asked to go to Atlanta for [mayoral candidate] Vincent Fort, who lost. I am asked to go to lots of places. We did send an email in Virginia, urging people to come out and vote.”

Thursday, as Sanders talked up his primary changes, a group of ex-Sanders organizers launched the Movement for a People’s Party, urging left-wingers to build something new outside the DNC.

“Regardless of what Bernie seeks to do, the majority of Americans have spoken and they’re saying what we need is a new party,” said Nick Brana, the movement’s founder. “It’s easier to start a new party than reform the Democratic Party. We saw that last month, when Bernie delegates were purged from the DNC.”

Brana was referring to a move that retired several at-large DNC members who supported Sanders in 2016, and another move that shuffled Jim Zogby, a Sanders backer, off the rules committee. Those moves, at the time, created uncertainty that the unity commission’s recommendations could ever get a fair vote.

The Brazile saga had scrambled that — while adding to the litany of criticism for the DNC. As he argued for the party’s structure to change, Sanders faced a question: How much would it matter? Would anything fix the brand of the DNC, or was it too tarnished?

“I don’t know,” Sanders said. “But independents are a majority of voters. If you don’t include them, your party is obsolete.”