Some of this may be due to the fact that a bet on Trump offers a potentially bigger payoff: a $1 bet on the incumbent will yield about $3 if he wins, while $1 wagered on Biden will only return about $1.50.

Biden holds a significant lead in most national polls. Meanwhile, the polls in key battleground states and some political forecasters are predicting he will win in a landslide. But studies have shown that political betting markets frequently outperform polls in predicting events.

“There is a clear view from the majority of users that the President could cause an upset,” Sarbjit Bakhshi, Smarkets’ head of political markets, said.

But Bakhshi noted that the average bet on Biden is twice that wagered on Trump, suggesting that those who think Biden will win are more confident than those gambling on Trump. As a result of this disparity, Smarkets betting odds still favor Biden, giving him a 65% chance of victory.

Bakhshi noted that there is also a sizable disparity between what gamblers think of Biden’s and Trump’s chances in several battleground states, and what forecasts based on polls in those states are projecting.

The political and sports data analysis site FiveThirtyEight, which simulates the election based on a system that ranks and aggregates multiple polls, now has Biden favored to win Florida, with a 65% chance, while gamblers on Smarkets think Trump still has the edge in the state with a 54% chance of taking its 29 electoral college votes.

Bettors are also less certain of Biden’s advantage in other key battlegrounds. They give Biden a 65% chance of taking Pennsylvania, compared with an 86% probability in FiveThirtyEight’s poll-based model. They give Biden a 53% chance of taking North Carolina, compared with 63% in the polling data site’s analysis.

Gamblers on Smarkets give Biden a 74% chance in Michigan and a 75% chance in Wisconsin, which is again significantly less than FiveThirtyEight’s odds of 96% and 94%, respectively.

And while big numbers for early voting in Texas have led some political analysts to speculate that the longtime Republican bastion is in play this year, bettors on Smarkets still give Trump a 72% chance of winning the state, compared with a 66% chance in the FiveThirtyEight poll-based analysis.

“Only time will tell if the betting markets know something the pollsters don’t,” Bakhshi said.

Smarkets is a closely watched betting site because the odds in its markets are set purely based on the amount of money being wagered on a particular outcome. This differs from many other British betting sites where a human expert or computer algorithm stipulates the odds in a way designed to protect the bookmaker from potential losses.