In the final few weeks of the presidential race, some polls and prediction markets are indicating we could have Donald Trump back in office come January 2025. For the first time since August, the former president overtook Vice President Kamala Harris in The Economist’s statistical model of America’s presidential election, and some other news outlets and political forecasters are predicting the same outcome.

Prediction markets like Polymarket and PredictIt also show Trump winning the election, but by a much steeper margin than some of the polls. As of Wednesday, Polymarket users have indicated Trump has nearly a 64% chance of winning the election, with Harris trailing at just 36%. PredictIt shows Trump in the lead with a 59% chance and Harris at 43%.

But what’s important to remember about Polymarket is that it’s a cryptocurrency-based prediction market—and Americans aren’t even allowed to trade on the website. As a result, Polymarket is conducting checks to verify that major users on the platform are based outside of the U.S., a person familiar with the matter told Bloomberg. 

This could be a key element in cracking the code on why Trump is seemingly pulling so far ahead of Harris, especially since only a handful of Polymarket users appear to be swaying the election odds. Starting earlier this month, four Polymarket accounts started pouring millions of dollars worth of bets that Trump would win the election.

As of Wednesday, Polymarket users Fredi9999, Theo4, PrincessCaro, and Michie had bet a collective $30 million that Trump would win the 2024 presidential election. Another Polymarket user, zxgngl, has been on a buying spree in recent days, betting more than $5 million worth of crypto on Trump retaking the Oval Office. With more than $35 million in bets being quickly poured into the presidential election market, it’s no wonder Trump appears to be ahead.

Alex Marinier, a venture capitalist who was one of the first to invest in Polymarket’s seed round in 2020, told Fortune it’s entirely possible “some large whale is placing large bets that move the market.”

“They're either super convinced that Trump would win, or explicitly to influence the market optics in favor of their candidate in an effort to help his odds of being elected,” Marinier said. “However, if the market believes that this whale bettor is, in fact, too optimistic on their candidate, then market forces should bring the market odds back to ‘correct’ market levels.”

Some political and betting experts have said prediction markets are the most accurate way to foresee election outcomes because people are betting real money on a particular outcome. The way prediction markets work is that traders buy shares depending on which outcome they think is more likely. Share prices or “odds” rise and fall depending on demand, so if the event happens the way the trader predicted, the contract or “bet” will rise to $1 and pay out—or fall to $0 if it does not.