Time is running out for the Democratic Party and, by this time next week, it will probably be too late for them to turn back. More than a third of the delegates to their national convention will be chosen next Tuesday, when 14 states including California and Texas hold their primaries. On the one hand, this means that the party’s agonizing struggle over its 2020 presidential nomination soon may be effectively over. On the other hand, if Vermont Sen. Bernie Sanders claims a decisive victory next Tuesday — which now seems likely — the “Anybody but Bernie” faction of the party will be pushed to increasingly desperate measures in their efforts to deny him the nomination.

Talk of a “brokered convention” at Milwaukee, with insiders scheming to prevent the avowed socialist from becoming the Democratic nominee, may be nothing but a fantasy to delight the imaginations of excitable journalists. Yet serious people in Democratic ranks are expressing fear that Sanders will lead the party to ruin in November, and to such people, stopping Sanders is the only hope of avoiding the unthinkable prospect of another four years for President Trump. Therefore, it is impossible to rule out any dirty trick that Bernie’s enemies within the party might use against him.

This is a problem that Democrats created for themselves. First, in 2018, Democratic National Committee chairman Tom Perez committed the party to “the most inclusive debate process in our history.” The first two rounds of debates, last June and July, featured 20 candidates, including such no-hope contenders as California Rep. Eric Swalwell, Ohio Rep. Tim Ryan, former Colorado Gov. John Hickenlooper, and Washington Gov. Jay Inslee. It was not until September that the field on the debate stage was narrowed to 10 candidates, and by then a lot of valuable TV airtime had already been wasted by candidates who would never make it as far as the Iowa caucuses. Now, with the hours ticking down to Super Tuesday, Democrats must be asking themselves, “Why did we do that?” And the answer is that, after facing claims that the 2016 nomination process was rigged in favor of Hillary Clinton, Perez and the DNC committed to these “inclusive” debates to demonstrate that there would be no such rigging in 2020.

The second crucial error Democrats made was letting former Vice President Joe Biden ride high for so long as the front-runner. In the early rounds of the televised debates, with so many candidates competing for attention, little attention was paid to Biden’s weaknesses. His advanced age made his unscripted appearances on the campaign trail an embarrassment of incoherent babbling, and he wasn’t generating any real grassroots enthusiasm in Iowa or New Hampshire. As long as he was leading the polls (as late as December 6, Biden led Sanders by double digits in the RealClearPolitics average of national polls), Democrats and their media allies handled Biden gently, with the presumption that he would be the eventual nominee. Biden’s main argument was his “electability,” and he continued to lead national polls up until the actual voting began, when Mister Electability began to lose, and lose, and lose again. His second-place finish in Nevada was an improvement over Biden’s dismal showing in Iowa and New Hampshire, but at this point he’s just playing out the string.

Biden’s last hope, the “firewall” of his campaign, is Saturday’s South Carolina primary, where polls still show him leading. Even if he wins there, however, it probably won’t revive his campaign because of a third error Democrats made — letting billionaires buy their way into the presidential race. Hedge-fund billionaire Tom Steyer is spending millions on TV ads in South Carolina, siphoning away votes from Biden, and financial-services billionaire Michael Bloomberg has spent something near $500 million blitzing the Super Tuesday states with advertising. Thus, if Biden wins in South Carolina, his margin will be smaller than it would have been without Steyer’s competition, and his chance to gain momentum on Super Tuesday will be blunted by Bloomberg’s big spending.

The biggest mistake Democrats made, however, was underestimating Bernie Sanders. In December 2018, influential progressive blogger Markos Moulitsas declared on Twitter, “I’ll call it now — Bernie won’t get more than 12% once the field shapes up. Likely single digits. Too many good progressives will run. Too few Bernie dead-enders left.” This reflected a widespread attitude that the Sanders challenge to Hillary Clinton in the 2016 primary campaign had been a one-off and that a more viable left-wing candidate emerge in the 2020 field. Certainly the prediction that “many good progressives” would run was correct, but none of Sanders’ rivals ever matched the solid base of support he brought to the campaign. The “Bernie dead-enders,” as Moulitsas called them, have proven to be more than enough. Long after such hopefuls as former Texas Rep. Beto O’Rourke, New York Sen. Kirsten Gillibrand, and California Sen. Kamala Harris were forced out of the race, Sanders and his “dead-enders” are still going strong.

Tuesday night’s debate in South Carolina was televised chaos, with candidates talking over each other, Joe Biden shouting gaffes at the top of his lungs, and Massachusetts Sen. Elizabeth Warren “just straight-up campaigning to be Bernie’s running mate,” as National Review’s Jim Geraghty observed. At one point, however, the topic turned to the issue of electability, with both Mayor Pete Buttigieg and Bloomberg warning that nominating Sanders would guarantee Trump’s reelection. “Bernie will lose to Donald Trump,” said Bloomberg, “and the House and the Senate and some of the state houses will all go red. And then between gerrymandering and appointing judges for the next 20 or 30 years, we’re going to live with this catastrophe.”

Of course, Republicans wouldn’t consider such an outcome a “catastrophe,” but Republicans won’t be deciding who gets the Democratic nomination. Democrats are caught in a trap of their own making. There are some pundits who say Sanders might actually do better against Trump than any of the other Democrats, and at this point in the campaign, it’s impossible to know what the result will be in November. But the time for Democrats to make their choice is getting short, and they alone must bear the consequences of their choice.