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WASHINGTON — The biggest policy-related fight roiling the 2020 Democratic field may not be over any of the increasingly ambitious proposals flooding the race, but the ways progressives would like to turn some of them into reality.

With the Senate and Supreme Court landscapes looking like a roadblock to legislative wins, a growing number of candidates are looking to change the rules of engagement should they win unified control of government.

A new network of progressive activists want the next Democratic president and Senate majority to make changes that would leave Republican lawmakers unable to block their bills and give Republican-appointed judges fewer opportunities to overturn them. And that's just the beginning.

“Maybe process is finally sexy again because people seem to care about this,” South Bend Mayor Pete Buttigieg told NBC News. “People are excited to talk about the future of the court or the filibuster.”

The movement feeds into broader Democratic concerns, exacerbated by President Donald Trump's popular vote loss in 2016, that the current system is antithetical to majority rule.

“The whole time Alexandria Ocasio-Cortez has been alive, Republicans have won the popular vote exactly one time,” Sean McElwee, co-founder of Data For Progress, said. “Despite that, they have control of the presidency, control of the Supreme Court, control of the Senate, and until recently, control of the House.”

Activists envision changing Senate rules and the judiciary as a lead-in to an array of structural reforms, like abolishing the electoral college, creating independent commissions to undo gerrymandered districts, and approving Washington, D.C., and Puerto Rico as states, in part to counteract a growing GOP advantage with low-population states in the Senate.

Late this week, former Rep. Beto O’Rourke became the second presidential candidate, following Buttigieg, to float expanding the Supreme Court to 15 seats and selecting members evenly along partisan lines, with some chosen by the justices themselves.

“What if there were five justices selected by Democrats, five justices selected by Republicans, and those 10 then pick five more justices independent of those who chose the first 10?” O’Rourke said in Iowa on Thursday. “I think that’s an idea we should explore.”

That idea didn't come out of nowhere.

Groups like Pack the Courts have been injecting it into the primary season bloodstream, hoping to replicate the success of "Abolish ICE," a concept activists moved from the fringes to the mainstream of the Democratic Party in 2018.

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Kate Kendell, the campaign manager for Pack the Courts, said in a phone interview last week that Buttigieg’s initial answers came in response to questions from individuals associated with Pack the Courts. Same with former Attorney General Eric Holder, who recently ruled out a presidential run and said at an event that Democrats should consider adding two more judges to the Supreme Court.

“Candidates should expect to be asked this question,” Kendell said, adding that ignoring the conversation would be at the “diminishment of their own credibility.”

While Buttigieg and O’Rourke have talked about restructuring how the court operates, Pack the Courts has advocated for simply adding more Democratic-appointed justices, which would require only a majority vote if the filibuster were eliminated.

Progressive activists say Republicans’ blockade of President Barack Obama’s nominee Merrick Garland and the contentious confirmation of Brett Kavanaugh under Trump along with dozens of federal judges have given them an opening to make a more sweeping case to Democratic voters about the court’s legitimacy.

“The discussion will arise around what version of reform people support, but the idea of just saying, ‘Oh well, we just have to live with all these Trump judges for the next 30 years’ is an untenable position,” said Brian Fallon, executive director of the progressive group Demand Justice and a former senior aide to Hillary Clinton’s 2016 presidential campaign.

In addition to Buttigieg and O'Rourke, Democratic presidential candidate Andrew Yang has tweeted that Democrats should consider adding “several justices.”

Many 2020 candidates still haven’t weighed in on ideas like expanding or reshaping the court, but at least one, former Rep. John Delaney, D-Md., is vocally opposed to it.

“[I]t is incredibly unfortunate that the Supreme Court has become so politicized, but I don't think our argument should be to make things worse,” he said in an email.

Even if they don't succeed — and it's highly unlikely in the short term — activists see an upside in convincing rank-and-file Democrats to adopt a more more hostile posture toward the other party's court appointees.

The debate has not broken along typical ideological lines. Instead, candidate’s resumes have been a better tell, with senators more reluctant to endorse changing legislative rules versus governors and mayors more eager to drop them.

“I think right now there's sort of two axes: ideology and willingness to fight,” Leah Greenberg, co-founder of the grassroots progressive group Indivisible said. “And they don't necessarily line up.”

Sen. Bernie Sanders, I-Vt., who frequently plants the field’s leftward flag on policy issues, has expressed unease with changes to Senate rules.

“I'm not crazy about getting rid of the filibuster,” Sanders said in a CBS News interview last month. “I think the problem is people often talk about the lack of comity and the anger. The real issue is that you have in Washington a system which is dominated by wealthy campaign contributors.”

Sanders is joined by many of his elected colleagues, who fear abandoning the filibuster would give the minority less say in legislation and open them up to retaliation once the other party regained control.

But at SXSW last week, Washington Gov. Jay Inslee told NBC News that candidates “cannot be serious about dealing with climate change in the next administration” unless they favored getting rid of the filibuster first.

“You have a number of senators who like to cling to senatorial privilege,” Inslee said. “It won’t work.”

Also at SXSW, former HUD Secretary Julian Castro told an audience that he would "rather not" eliminate the filibuster, but would endorse the idea if it became an obstacle to universal health care.

Among legislators running for president, the idea has less traction. Sen. Elizabeth Warren, D-Mass., has said “everything stays on the table” if Democrats win. But Sen. Cory Booker, D-N.J., strongly opposes changing the filibuster. Sen. Amy Klobuchar, D-Minn., signed onto a bipartisan letter defending the filibuster in 2017. Sen. Kamala Harris, D-Calif., told a town hall questioner she was “conflicted” over the idea.

“If you’re not able to get 60 votes on something, it must means you haven’t worked hard enough,” Sen. Kirsten Gillibrand, D-N.Y., said in an appearance on "Pod Save America." She later said she would “think long and hard about it.”

Senate rules are definitely not off-limits these days: Republicans ended filibusters on Supreme Court nominees to confirm Justice Neil Gorsuch after Democrats did the same for federal judges under Obama.

Republicans, however, have resisted Trump’s own repeated demands to end the filibuster on legislation.

But they didn’t turn to Democrats to reach 60 votes on major bills either, instead using a procedure known as budget reconciliation — which requires only a majority of senators — to pass a $1.9 trillion tax cut and attempt to repeal the Affordable Care Act.

Reconciliation could be a fallback for Democrats if, but there are strict limits to the process that could make large-scale health care or climate legislation difficult. And so whatever the details, politicians and activists see broader issues around structural reform gaining steam, meaning they can expect plenty of new litmus tests before the campaign is done.

“If our democracy is warped, every policy issue we care about is going to be harder to solve,” Buttigieg said.