Midterm elections are generally seen as less important than presidential elections. The stakes seem lower, which means fewer people turn out to vote. Most of the time the party controlling the White House takes losses, and this predictability can make midterms seem less important too: what can one voter do against the strength of the political tides? But occasionally there are midterms whose stakes rise beyond whether or not the president’s party will be able to pass new laws, and instead concern the whole future of the American republic. This year is one of them.

That’s because this year, the majority of Republican candidates running for Congress, governor’s mansions, and other key statewide offices have denied or questioned the results of the 2020 presidential election. Donald Trump’s attempted coup failed in 2020 because officeholders at the federal and state level refused to go along with it. This year’s midterm elections could change all of that, producing a set of Republican officials willing to extinguish American democracy.

There have been several other midterms in American history which foreshadowed chaos and violence to come. In 1858, the anti-slavery Republican party won a plurality in the House of Representatives, exacerbating the divisions which would lead to the civil war. In 1874, the Democratic party won a massive majority in the House, which turned out to be enormously consequential amid the contested election of 1876. In return for not attempting to block the inauguration of the Republican candidate Rutherford B Hayes, House Democrats demanded the withdrawal of federal troops from the south, ending Reconstruction.

Both of these midterms were momentous, but they also differed from our present situation. Abraham Lincoln’s election in 1860 rent the Union, but nobody doubted that he had been legitimately elected president. On the other hand, widespread violence and fraud meant that the election of 1876 was genuinely contested, and even today the question of “who really won?” is difficult to answer. The end of Reconstruction had horrific consequences for African Americans in the south, but the basic institution of competitive elections lived on, and with it the possibility for future change.

Never before in American history has there been an organized movement which was only one vote away from having the motivation and opportunity to make that election America’s last. Never that is, until now. Today’s anti-democratic movement is propelled not by genuine controversy or scandal, but rather by their commitment to ending competitive elections in the United States. There is no other way to interpret their belief that only one side, the Republicans, can legitimately be considered to win, and the plans that they hold to make this belief a reality.

The problems can be expected to start this November, when Republican candidates who lose will question the validity of the results and try to stir unrest. State officials who do win will begin to act on their plans to sabotage future polls by centralizing power in their own offices, de-registering millions of voters, and moving to error-prone hand-counting systems. Then, if voter suppression doesn’t prevent a Democratic win in 2024, they’ll just suppress the evidence instead and announce that they are sending Republican electors to the electoral college. Meanwhile, the majority of Republican House candidates in 2022 are election-deniers, and a Republican-controlled Congress might attempt to sabotage the certification of the presidential vote on 6 January 2025.

Each of these potential points of failure threatens the integrity of the 2024 presidential election. The breadth and depth of the anti-democratic movement also means that they are likely to pose other problems which are difficult to anticipate. Whatever means they find of sabotaging the vote, it would be foolish to rely on the conservative-dominated supreme court to stop them, particularly if the country has been plunged into civil unrest and violence.

That’s why measures like reforming the Electoral Count Act, something which Congress may take up in the lame duck session after the midterms, are not enough. Legal tinkering can only go so far in the face of a dedicated movement, especially if it is willing to go outside the law and provoke violence on the streets. The only thing that can avert an impending crisis is to keep Republican party’s election saboteurs out of office. Yet the Democratic party has decided to largely fight the midterms on other issues which they think motivate voters more effectively. And while it’s true that very few voters do identify threats to democracy as the most important issue facing the country, this is partly down to a failure of Democrats and the media to communicate just how bad things might get.

At least part of Democrats’ closing message in these elections must be dedicated to changing that. Voters need to understand that the threat to democracy is very real, and that bad choices this year could lead to complete breakdown in 2024. It might be impossible to stitch the national fabric back together or to return to free, competitive, reliable elections afterwards. Democracy is not some arcane or marginal topic but is at the very heart of America’s ability to undo its mistakes and move forwards as a nation. That makes these the most important midterms in American history. It’s way past time to communicate the stakes clearly.

• Andrew Gawthorpe is a historian of the United States at Leiden University and host of the podcast America Explained