Early in Thursday night’s Democratic debate in New Hampshire, Hillary Clinton took a curious tack in answering Bernie Sanders’s accusations that she’s too beholden to Wall Street: She went after the Vermont senator for voting for a bill that her husband signed into law when he was president (and which she herself did not oppose). “While we’re talking about votes,” Clinton said, “you’re the one who voted to deregulate swaps and derivatives in 2000, which contributed to the over-leveraging of Lehman Brothers, which was one of the culprits that brought down the economy.” 

This was a reference to the Commodity Futures Modernization Act of 2000, which Sanders did indeed vote for—a rare (possibly lone) example of him supporting the broader policy of financial deregulation that Bill Clinton carried out. The fact that Hillary Clinton was put into the anomalous position of blaming Sanders for agreeing with Bill Clinton highlights one of the paradoxes of the ideological battle between the former secretary of state and the Vermont senator: Although Bill Clinton is rarely mentioned by name, his legacy is at the core of what Bernie Sanders and Hillary Clinton are arguing about. When Bernie Sanders accuses Hillary Clinton of not being a real progressive, he’s really saying that she is a neoliberal sellout like her husband. 

Both political parties are now having debates about the legacy of former presidents. The Republican debate, spurred on by Donald Trump’s digs at George W. Bush, seems a more natural one to have, since Bush was a divisive figure in the nation at large and in his own party at the end of his presidency. The rise of Donald Trump and Ted Cruz within the GOP is proof that many Republicans are uneasy with the political inherence left by George W. Bush on foreign policy (the Iraq war and nation-building, free trade) as well as domestically (immigration reform). “Jeb, why did your brother attack and destabilize the Middle East by attacking Iraq when there were no weapons of mass destruction? Bad info?” Trump tweeted last OctoberIf George W. Bush sold himself as a compassionate conservative, Trump and Cruz are decidedly conservatives with no pretense of compassion.

By contrast to Bush, Bill Clinton is warmly remembered by many Democrats. The surprise is that Sanders has been able to make a formidable attack by focusing on aspects of the Clinton legacy that are no longer popular among party members. The debate about the current Democratic president has been far more muted by contrast. Clinton has taken on the mantle of being Barack Obama’s heir, the one who can best defend and consolidate the current Democratic president’s legacy. Sanders has a more complicated relationship with Obama, praising him for helping the country recover from the Great Recession of 2008, but also saying that the country now needs to move in a more aggressively progressive direction. In the debate tonight, Sanders said that Obama did a “fantastic job” and “excellent job” on the economy even though he disagrees with the president on trade. 

But if Sanders is ambivalent about Obama, he’s doesn’t hold back when it comes to Bill Clinton. And this puts Hillary Clinton in a tough bind. It’s hard for her to disavow the presidency of the man she is married to—and whose policies she defended vigorously as first ladybut Clinton is acutely aware that the Democratic Party has moved on from 1990s Clintonism and is a much more progressive party.

Consider the litany of ideological sins that Sanders checks off to prove that Hillary Clinton is a moderate and not a progressive. Many of them are legacies of the Bill Clinton presidency, when the Democratic president tried to triangulate between the left of his own party and the Republican right. Sanders’s list of evidence is long: Clinton supported NAFTA; championed the 1996 welfare reform; supports the death penalty in federal cases; supported the Defense of Marriage Act; opposes re-instating Glass-Steagall; supported Don’t Ask, Don’t Tell; and backed “three strikes and you are out” sentencing. They’re all centrist Democratic policies that Bill Clinton enacted in opposition to the left wing of the Democratic Party in the 1990s. 

The Sanders-Clinton battle is over the future direction of the Democratic Party, but it also inevitably calls into question the legacy of the past. Not the least revolutionary aspect of Sanders’s agenda is the wholesale rejection of Bill Clinton’s political legacy. Hillary Clinton’s awkward invocation of Lehman Brothers on Thursday highlighted her struggle to find a balance between her own political past and the very different politics of her party in 2016. 

Is Sanders’s attempt to stick Hillary with the legacy of her husband working? There’s no way to accurately gauge its effectiveness, but a telling point is that by attacking Bill Clinton, Sanders has made himself the politician of change in this race. Not surprisingly, this has helped him do better among young voters, who fueled his strong performance in the Iowa caucuses, while Hillary is winning with the voters who lived through her husband’s presidency—and perhaps are still nostalgic for it.