On Thursday, Democratic high rollers got their wish when former Massachusetts governor Deval Patrick entered the presidential race. For weeks, large-dollar donors have been panicking about their party’s top four candidates — Joe Biden, Sen. Elizabeth Warren (Mass.), Sen. Bernie Sanders (I-Vt.) and Pete Buttigieg — and trying to find another qualified, electable Democrat to get in the race. Patrick and former New York mayor Mike Bloomberg, if he officially gets in, seem to be answers to their prayers.

But these late entrants and their supporters might be underestimating the challenges ahead. Most primary candidates spend the better part of the year (or in John Delaney’s case, years) building up a campaign infrastructure, gathering donors, carving out a base, finding a unique message and rebooting when necessary. Late entrants usually fail — they try to scale up too much in just a couple months, make mistakes and don’t have time to recalibrate. If Democrats really wanted to introduce a new variable — someone who could either win or knock a couple people out of the top four — they need to look outside the box. And beyond the fact that most of those wild card candidates absolutely, positively aren’t running, many of their potential candidacies have real pitfalls, too.

Michelle Obama would be the perfect late entrant in the Democratic race. Obama has nearly universal name recognition; she’s the most admired woman in America according to Gallup; and an October Boston Herald poll found that she would immediately take the lead in New Hampshire were she to enter the race. Democrats love and trust Barack Obama, and even more so than her husband’s former vice president, Mrs. Obama could harness that goodwill and her own well-developed personal brand to quickly build a base. Mrs. Obama absolutely isn’t going to run, but if she did, she’d have a decent shot of winning. And if she had started running six months ago, this primary might already be functionally over.

The thought of Hillary Clinton 2020 isn’t nearly as fun for Democratic voters — most don’t want to relive the 2016 election — but her entry into the race could shake things up. Clinton could (correctly) point out that she won the popular vote, claim exoneration in the matter of her email security or lack thereof, talk up her long record of experience and use the same deep roots in the party that helped her win the nomination last time. Clinton might have trouble talking about electability: She’s the only Democrat in history to lose a presidential election to Donald Trump. But she could still command some loyalty in the base and kneecap Biden.

Al Gore also wouldn’t have a great electability case either: He lost to George W. Bush in 2000, is widely seen as a wooden campaigner and has spent the past 19 years mostly outside electoral politics. But, as the most famous environmentalist alive, he might be the most effective iteration of the single-issue climate crisis candidate we’re seen so far. And at a spry 71 years old, he might be able to avoid some of the age-related questions that dog Sanders and Biden. I doubt Gore would win the Democratic primary, but his entry could weaken the progressives by splitting off a piece of the activist, pro-environment left.

The last candidate on my list is Oprah Winfrey. Winfrey has been discussed as a possible left version of Trump — an outsider with amazing communication skills who has insights into the Democratic electorate and might be able to instinctively spot policy appetites or collective emotions that traditional Democrats can’t. Winfrey, like Clinton, Gore and Obama, is well known and has a fan base that would quickly rally to her. Still, the dynamics are different: Trump won by targeting a previously under-targeted group — white, downscale, not-highly-religious immigration restrictionists — and it’s not clear that there’s a similarly underserved niche in the Democratic Party. It’s hard to predict what effect Winfrey would have on this race except that it would be wildly disruptive.

Other potential late entrants could make noise. As others have pointed out, an Eric Holder run would signal that Biden has fully lost the confidence of the Obama-era establishment. Sherrod Brown might be able to cripple Biden if he jumped in late and executed a flawless Rust Belt strategy. But most other late entrants have the same problems as Bloomberg and Patrick: They’re normal politicians who are trying to build a movement on an extremely truncated timeline. They both have an outside chance of winning, sure. But if Democratic donors are serious about shaking up the race, they might want to think bigger. And if what they really want is a different front-runner, they might look to the candidates they already have to choose from.

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