Joe Biden spent most of last night’s debate swatting aside attacks on his positions from years past. But none of these attacks touched on one of his most troubling beliefs: his insistence that our constitutional system can be our salvation, helping us forge consensus and check the abuse of power so rampant under President Trump. This belief puts him out of step with his party and the times.

Other top Democratic contenders, particularly Elizabeth Warren and Pete Buttigieg, have disagreed, forcefully backing constitutional reform. Shortly after announcing his candidacy, Buttigieg said, “I think the first thing you have to do is move on democratic reform….We are living in a time when we’ve got to fix the engine of our democracy,” suggesting structural reforms that included replacing the Electoral College and eliminating the Senate filibuster.

Warren and Buttigieg are right to call for these reforms. After all, the Constitution was the result of numerous compromises designed to ensure that all 13 colonies, slave and free, small and large, would acquiesce to the governing system. The resulting structure, never particularly equitable or democratic, has been exposed as fatally flawed. Agreed upon more than two centuries ago, it has allowed deep political polarization to flourish as huge ideological disparities grow between white, predominately rural voters and those in more diverse suburban and urban areas.

Nowhere is this clearer than the U.S. Senate, the institution in which Biden served for more than three decades.

The aristocratic Senate was designed to balance the democratic House, protect the rights of small states and provide representation for states themselves, with senators originally selected by state legislatures. While the 17th Amendment made the institution notionally more democratic by establishing popular elections for senators, it did not go far enough. As constitutional scholar Sanford Levinson observed, the “equal-vote rule in the Senate makes an absolute shambles of the idea that in the United States the majority of the people rule.”

This structure has always proved problematic. For many decades it preserved slavery before a bloody Civil War ended the odious practice. Then, for another century, powerful Southern senators representing barely 30 percent of the national population were able to take advantage of the equal footing doctrine, augmented by the filibuster (which empowers Senate minorities), to maintain Jim Crow segregation while disregarding the post-Civil War amendments meant to ensure racial justice. Anti-lynching legislation and robust voter protection bills died in the Senate, although the language of the 14th Amendment, with its equal protection and due process clauses, and 15th Amendment, with its ban on race-based voting restrictions, should have made them unassailable.

Southern senators even worked to exclude African Americans from many benefits of New Deal social insurance programs by encouraging discrimination under the National Industrial Recovery Act, failing to enforce minimum wages for blacks under the Fair Labor Standards Act and promoting racial covenants for mortgages granted by the Federal Housing Administration. It wasn’t until the mid-1960s, when an unshakeable social movement rose up to demand change, that civil rights proponents overcame the South’s power in the Senate.

Other corrosive features of the Senate, however, remained obscured so long as the country’s tremendous wealth allowed the federal government to solve pressing problems without demanding much sacrifice. Post-Civil War policies ranging from infrastructure spending to the creation of the Department of Agriculture were approved because the country could afford them — and because they benefited all regions, which meant most senators weren’t interested in obstructing them.

Although the New Deal programs of the 1930s and the Great Society programs of the 1960s were more expensive, the U.S., with the largest economy in the world and a healthy rate of taxation, had sufficient budgetary resources.

But the rising challenges to U.S. economic dominance over the past half-century have revealed that the Senate’s structural weaknesses could impact almost any policy issue facing the country. During the 1970s, the rise in energy insecurity threatened continued economic growth and tightened federal budgets. This was happening as the disparity in state populations was intensifying, as Americans migrated from the struggling Rust Belt to the thriving Sunbelt.

These dual changes meant that, for the first time, Congress had to make hard choices just as the Senate became even more unrepresentative. If not for the equal representation doctrine, senators representing a majority of Americans could have developed policies addressing national problems. But because senators representing small-state parochial concerns had outsized power, they were able to either prevent action or dilute legislation. The results were disastrous.

In the 1970s, Presidents Richard Nixon, Gerald Ford and Jimmy Carter all failed to enact comprehensive plans to ensure American energy independence as oil imports soared. Carter and House Speaker Tip O’Neill (D-Mass.) were able to push a visionary conservation bill through the House of Representatives. Despite broad popular support, however, the legislation was watered-down in the Senate where small rural states with large fossil fuel sectors had enormous power.

This was just the beginning, as the equal footing doctrine and the filibuster, which senators had started to use at an accelerating pace, conspired to increasingly thwart policies backed by a majority of Americans.

In 1993, Bill Clinton tried to gain passage of universal health-care legislation, at a time when Americans said it was the second-most important problem facing the nation, yet no bill even came up for a vote because it was clearly doomed in the Senate. In 2007, George W. Bush lobbied hard for comprehensive immigration reform, which was supported by the House and had bipartisan backing in the Senate, but it failed to survive a filibuster. In 2009, Barack Obama supported a public option to compete with private health insurance companies, but despite passing the House easily, it was dropped to woo a single senator, whose vote was necessary to overcome a filibuster. Also in 2009, House Speaker Nancy Pelosi (D-Calif.) muscled a cap-and-trade program to address the climate crisis through her chamber, only to see it fail to reach the Senate floor, despite the fact that Obama supported it and Democrats controlled 59 Senate seats.

The repeated failures to address these same pressing issues make one thing clear: we’re not tackling our problems. And the Senate is a major reason why.

Absent the Senate, some form of legislation would have almost certainly passed in each of these cases. Always an institution that gave outsized power to small states, the Senate has become a body where those representing a tiny portion of Americans can constantly frustrate the will of the majority. And due to geographical sorting, this is likely to get far worse. Within two decades, only 32 senators will represent 70 percent of our nation’s population.

This is why progressive candidates like Warren and Buttigieg are pushing for constitutional reform. There is a mismatch between our governing structures and contemporary needs, particularly regarding the Senate. A straightforward fix would be abolishing the filibuster. Many have argued that this procedural rule is unconstitutional, because it subverts the intentions of the Founders by requiring a supermajority vote to pass legislation. Ideally we would also go further, passing a constitutional amendment eliminating the equal footing doctrine and mandating proportional allocation of Senate seats. But the problems in our political system — and language in the Constitution itself — makes such a sensible change difficult.

But that doesn’t mean that progressive candidates shouldn’t be bold, or even radical, in their critiques of the institutions that are failing us. Acknowledging how the Senate thwarts democracy and how other parts of our governing charter, like the Electoral College and the amendment process itself, provide electoral minorities with disproportionate power is a critical first step in building the popular will to change these flawed structures.

Joe Biden seems to think that the system isn’t broken, only our politics. But our politics play out in a constitutional structure that distributes power unevenly, often undermining the will of the people, making governance intractably difficult and allowing rampant abuses of power when the president rejects the norms that should check him. The Constitution was always a flawed document. Our political representatives should acknowledge this and help guide the way to meaningful change that distributes power back to the people.