At a campaign stop in Iowa, Democratic presidential candidate Tom Steyer embraced a radical proposal to counter Republican domination of the Supreme Court — court-packing.

After Justice Antonin Scalia died in 2016, stripping Republicans of their Supreme Court majority in the process, Senate Majority Leader Mitch McConnell promptly announced that he would not allow anyone President Obama nominated to fill this vacancy to be confirmed. After President Trump won the 2016 election, Republicans confirmed Neil Gorsuch to fill the vacancy left open by Scalia’s death. Gorsuch is now one of the most conservative justices on the Court.

Republicans claimed that, in Sen. Chuck Grassley’s words, “it’s been standard practice over the last 80 years to not confirm Supreme Court nominees during a presidential election year,” but this claim appears to be entirely made up. At least 14 past justices were confirmed in a presidential election year — the most recent was Justice Anthony Kennedy in 1988.

In a video posted on Wednesday, Steyer says that he is “for” expanding the Court, arguing that Republicans “have been cheating.”

“When I think about the Supreme Court,” Steyer told a voter who asked about court expansion, “let us remember why we have the Supreme Court we have.” The answer, according to Steyer, is that “Mitch McConnell refused to allow President Obama’s choice to ever be brought up” for a hearing and a confirmation vote.

Though the Constitution provides that a Supreme Court shall sit at the apex on the judiciary, our founding document is silent about how many justices sit on the Supreme Court. A 1789 law established a six-justice Court, and the number of justices ebbed and flowed during the 19th century — swelling to 10 justices under President Abraham Lincoln before settling into a nine-justice configuration under President Ulysses S. Grant.

After a reactionary Supreme Court struck down several New Deal policies, President Franklin Roosevelt proposed expanding the Court to as many as 15 justices — although this proposal did not fare well politically, to say the least.

Steyer, it’s worth noting, is not the only Democratic presidential candidate who has floated court-packing as a counter to the tactics that placed Gorsuch on the Supreme Court. Former South Bend, Indiana, Mayor Pete Buttigieg suggested expanding the Court’s membership to 15 but also proposed having five of those justices selected in a process intended to minimize partisanship. Sen. Elizabeth Warren hasn’t fully embraced court-packing, but she told Politico that “it’s a conversation worth having.”

The party’s two frontrunners, former Vice President Joe Biden and Sen. Bernie Sanders, both oppose court-packing.

Court-packing is a dangerous tactic — but it could become necessary

Before Scalia’s death, and McConnell’s efforts to keep that seat in Republican hands, court-packing was virtually unthinkable.

Roosevelt offered his court-packing plan shortly after winning reelection in a landslide, and the popular president did so while the Court was actively sabotaging his efforts to end a historic economic crisis. But even Roosevelt was not able to build majority support for the idea. Many historians mark his court-packing plan as the moment that shattered his coalition and ended his ability to push liberal legislation through Congress.

As a practical matter, courts often depend on voluntary compliance to effectuate their orders. The South’s campaign of “massive resistance” to Brown v. Board of Education (1954) largely succeeded for 10 years. Public school segregation remained widespread in the Deep South until Congress enacted the Civil Rights Act of 1964, which gave the federal government additional tools it used to pressure schools into integrating.

A similar story could play out if Democrats resort to court-packing in order to preserve liberal victories. If a packed Supreme Court reinstates Roe v. Wade (1973) after a conservative Court overrules that decision, many red states are likely to launch a new campaign of massive resistance.

That said, I’ve written that there is one entirely possible scenario where court-packing could be justified: if the Supreme Court grows so hostile to voting rights that the only way to preserve competitive elections in the United States is to eliminate the Court’s anti-democratic majority. In this circumstance, Democrats might conclude that court-packing was a less terrible option.

Steyer’s embrace of court-packing is interesting not because he is likely to implement it himself — Steyer’s campaign for the Democratic nomination in eighth place, according to the RealClearPolitics polling average. Rather, Steyer’s support for court-packing is interesting because he has a history of spending lavishly to bring ideas on the political fringes into the mainstream.

As of January 2019, Steyer had reportedly spent $50 million on his “Need to Impeach” campaign targeting Trump.

Steyer is both a billionaire and a longtime activist in the fight against climate change. Meanwhile, the Supreme Court’s Republican majority has signaled loudly that they plan to strip the Environmental Protection Agency of much of its regulatory power. It’s not hard to imagine a future where Steyer grows so frustrated with the Court’s efforts to stop environmental regulation that he starts writing big checks to push a court-packing agenda.