For most of the primary, “anything can happen” has been the mantra of reporters, analysts and pundits alike. But that’s not really true anymore. The top-tier candidates – Joe Biden, Elizabeth Warren, Bernie Sanders and Pete Buttigieg – all have real support in early states and a plausible path to the nomination. The bottom-tier candidates are a grab bag of low-polling long shots and billionaires who theoretically could win but are probably just burning their cash.

Only one candidate falls into neither category: Sen. Amy Klobuchar (D-Minn.). Klobuchar sits between the top and the bottom tier, making her the race’s real wild card. If everything goes right for her, she might be able to post a solid showing in Iowa, stay alive and make real waves in the race. But she’s not strong enough to be placed in the top tier. Whether she booms or falls short is one of the biggest questions of the night of the Iowa caucuses, and could help upend the race down the road.

According to my average of recent Iowa polls, Klobuchar has the support of 7 percent of Iowa voters. To the untrained eye, that might not sound like a lot more than someone who is stuck between 0 and 1 percent of the vote. But, statistically speaking, candidates who have some support aren’t doomed because they have what could be called a “long right tail.”

This graphic, generated by the same mathematical tools I use to generate the Post Opinions Iowa Simulator, displays the range of the vote candidates who are at roughly 7 percent in the polls with 20 days to go until an election could plausibly win once voters head to the polls. The possible vote percentages for Klobuchar run left to right on the horizontal axis (from 0 to 60 percent), and the height of the big blue curve gives us a sense of how likely each possibility is. The curve is tall around 6 percent and short around 30, which means that 6 percent of the vote is a much more likely final result for Klobuchar than 30 percent.

This graph tells us two things about Klobuchar: that she’s probably not going to win, but that she’s not out of the race. According to my calculations, Klobuchar is likely to land somewhere between 2 percent and 18 percent of the vote, which probably won’t be enough to rocket her past the top-tier candidates. But the graphic takes a while to fully taper off to the right. That means Klobuchar has an outside chance of getting 20 percent or more of the vote, which could make her competitive with some of the other top-tier candidates.

If Klobuchar were to win, she’d likely follow the “Iowa cyclone” path described by my colleague Henry Olsen. Occasionally, candidates who amass a small but strong following, such as Rick Santorum in 2012 or Marco Rubio in 2016, can surge at the last moment, beat their polls and suddenly become much more competitive in the primary as a whole than they otherwise would have been. Klobuchar could do this, as Olsen points out, by appealing to the center-left: attracting moderates who think Buttigieg is too young, Biden is too old, and Sanders and Warren are too far left.

But if Klobuchar fails to mount a comeback such as Rubio or Santorum, it may be the end of the road for her campaign. Her electability pitch may sound thin to voters if she loses to four other candidates, one of whom is a random former mayor from South Bend, Ind., especially if she does so in Iowa after touting her Midwestern appeal. Moreover, if Biden or Buttigieg were to win, the moderate-problem-solver mantle would likely be out of Klobuchar’s reach.

And the caucus process can be unforgiving for lower-polling candidates. At each caucus site, candidates who get 15 percent of the vote or less are deemed “non-viable” and their supporters are freed up to get behind one of the viable candidates. If Klobuchar is stuck at, say, 8 percent in the polls, she might become non-viable at some caucus sites and lose voters in the second round. In that case, Klobuchar might perform respectably in the “first preference” tally of the vote but see her numbers diminish in other official tallies that take the caucus rules into account.

And that’s why Klobuchar is a tricky case. She doesn’t have nearly as clear a route to the nomination as do Biden, Buttigieg, Warren or Sanders. But her path is noticeably wider than the likes of John Delaney and Deval Patrick. A Klobuchar nomination isn’t impossible, but it would take a very impressive run of luck and skill.