Surveys show that a large majority of American citizens across the political spectrum oppose the U.S. Supreme Court’s Citizens United decision that opened the door to unlimited political spending by global corporations and powerful unions. Yet when asked about the prospect of passing a constitutional amendment to reverse the decision, too many people argue that it would be “too hard,” even “impossible.”

This argument lacks historical perspective. Every step on the path to fulfill the promise of the American Revolution was “too hard,” but Americans did it anyway. Hard, yes; yet constitutional amendments have come in waves during times of challenge — and Supreme Court obstinacy — much like our own.

The Bill of Rights and the post-Civil War amendments may be the most well-known examples, but this pattern has recurred. A generation after the Civil War renewed the promise of American equality and democracy, for example, the Supreme Court began elevating money to a privileged place in the Constitution. It struck down basic public-interest laws, including the minimum wage, worker safety, the federal income tax and even child labor laws.

The American public took matters into their own hands during the Progressive era at the turn of the 20th century. With the 16th amendment in 1913, Americans reclaimed the power to levy a progressive income tax, without which many of President Franklin D. Roosevelt’s New Deal social programs would not have been possible.

The 17th amendment that same year provided for popular election of U.S. senators. This replaced the old system of election by state legislatures, in which, according to the New York Times, a millionaire, either by outright bribery or contributions to a party’s campaign coffers, could buy a Senate seat “just as he would buy an opera box, or a yacht or any other luxury in which he could afford to indulge himself.” Finally, with the ratification of the 19th amendment in 1920, women gained the right to vote after a struggle that had lasted for more than half a century.

Four decades later, two additional constitutional amendments removed further barriers to political equality. The 24th amendment in 1964 protected the right of all Americans to vote in federal elections, regardless of the ability to pay a poll tax. President Lyndon B. Johnson hailed “the triumph of liberty over restriction, declaring “there can be no one too poor to vote.” The 26th amendment in 1971 reduced the voting age from 21 to 18, which ensured that young adults eligible to serve in the armed forces were able to vote.

Each of these fights required hard work, tough challenges and resilience. This is as it should be. Constitutional amendments are warranted only by what James Madison called “extraordinary occasions.” That is why enacting and ratifying an amendment to the U.S. Constitution is no easy matter.

The situation we face today with regard to campaign finance is one of those “extraordinary occasions.” Overwhelming political spending by a relative handful of organizations and extremely wealthy people is marginalizing the voices and participation of most Americans. In the 2012 presidential election, a few dozen super-PAC donors exceeded all the contributions of $200 or less from the nearly four million donors to the Romney and Obama campaigns combined.

The 2014 midterm elections brought even greater concentration of big spenders. Indeed, virtually all political spending now comes from far less than 1 percent of Americans, and increasingly from global corporations using “dark money” entities to obscure the source.

The result of such unbalanced concentrated power in the U.S. system of government is exactly as Madison and other founding fathers feared: failure of effective republican self-government due to powerful factions and corruption.

The Supreme Court that issued the Citizens United decision will not correct itself. Over the past five years, the sharply divided court has only expanded the ruling. In a series of decisions, it has invalidated traditional powers of the states, striking down longstanding anticorruption laws in Montana and nullifying new approaches to strengthen voter-funded elections in Arizona and Maine. In the 2014 McCutcheon decision, the court struck down a limit as high as $123,000 on total contributions to candidates for Congress. In Hobby Lobby and other recent decisions, courts are empowering corporations to seek even more exemptions from laws based on ever-broadening theories of corporate rights, including speech, religion and equal protection as “persons.”

To hope that the current court will fix things is folly. That is why the 28th amendment is necessary to overturn Citizens United, just as Americans have used the amendment process to overturn the Supreme Court six times before.

The 28th amendment would restore the power of Americans to enact reasonable election spending laws that protect the political equality of all. Specifically, the Democracy For All Amendment, which more than 165 senators and representatives have introduced, restores the authority of Congress and the states to enact election spending laws and to distinguish between human beings and corporations in doing so.

Five years after Citizens United, it is time to accept the historical gravity of our situation. It is time for Americans of all political viewpoints to come together to win the 28th amendment — and to renew U.S. democracy again.