Former President Donald Trump enjoys a nearly 10-point lead in Pennsylvania on an online betting platform.

Polymarket, which allows users to place wagers on events such as presidential elections, found a 55% chance of Mr. Trump winning Pennsylvania and a 46% chance for Vice President Kamala Harris as of Tuesday.

Mr. Trump’s odds of winning hadn’t been this high on Polymarket since President Biden dropped out of the race and Ms. Harris took his place. The odds of him winning hit a high of 67% one week before Mr. Biden dropped out.

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The two candidates’ odds were all but equal from the end of September to roughly Oct. 2.

There is no way to be sure what caused the rise in confidence of a Trump win in the Keystone State. Ploymarket also doesn’t limit individual bettors.

On an X account that is thought to be run by Tesla owner and X CEO Elon Musk, DogeDesigner, a post was shared Sunday showing that Mr. Trump leads in betting markets, crediting it to Mr. Musk campaigning with Mr. Trump in Butler County, Pennsylvania. The two were in Butler on Saturday, and Mr. Trump did see a three-point jump from Friday to Saturday on Polymarket.

In another post that Mr. Musk reposted from DogeDesigner, he said betting market odds are “more accurate than polls, as actual money is on the line.”

Polls still show Ms. Harris leading in Pennsylvania. According to the pooling average calculated on the FiveThirtyEight website, Ms. Harris leads Mr. Trump 48% to 47.3% in Pennsylvania, which is a much slimmer chance than on Polymarket.

Pennsylvania is a key battleground state that Mr. Trump won in 2016 but swung back to Democrats in 2020.