Election data expert Nate Silver said over the weekend that Vice President Kamala Harris had missed a “huge opportunity” by choosing her running mate. Polls suggest this move could cost the Democrat a crucial swing state.

The founder of FiveThirtyEight wrote in his Silver Bulletin newsletter on Sunday that the 59-year-old “missed a huge opportunity to move to the center by choosing Tim Walz (Governor of Minnesota) instead of Josh Shapiro (Governor of Pennsylvania).”

Silver was responding to a New York Times/Siena College poll that found that nearly half (47%) of likely voters think Harris is too liberal, a reflection of her failed 2020 presidential campaign in which she held several far-left positions.

“(Harris) is a more talented politician than she showed in 2019, and it’s a shame that her campaign this year was run by people who apparently thought Elizabeth Warren was a right-winger,” Silver wrote. “I think Walz was a pretty good choice on his own merits, but when given the opportunity to send a tangible signal about the direction her presidency would take, (Harris) fell back into 2019 mode.”

The possible selection of Shapiro had sparked a backlash from far-left Democrats because of his support for Israel. Many critics said criticism of Shapiro, who is Jewish, had its roots in anti-Semitism, and Silver wrote on Sunday that “the fact that a tiny minority of progressives objected to Shapiro was, if anything, an argument in Shapiro’s favor.”

In addition to the attacks from the left, the team of Democratic Senator John Fetterman of Pennsylvania reportedly advised Harris’ camp against nominating Shapiro, denouncing him as a political opportunist.

Before Harris’ announcement, Philadelphia Mayor Cherelle Parker edited a video suggesting the governor was the vice presidential candidate, apparently angering some of Harris’ allies.

People close to Harris claim that she chose Walz as her running mate because of the good personal relationship she has built with him.

Shapiro was seen as a potential running mate who could bolster Harris’ support in the Keystone State, whose 19 electoral votes are considered crucial to the outcome of the race.

Silver noted on Sunday that the vice president is “performing poorly among white voters without college degrees, rural voters and older voters: the types of voters who are present in large numbers in blue-wall states like Pennsylvania.”

As of Tuesday, Silver’s model gave 78-year-old former President Donald Trump a 65 percent chance of winning Pennsylvania and a 64.4 percent chance of winning the election, a new high for the Republican nominee since President Biden ended his re-election bid on July 21.

The Times/Siena poll was released two days before Harris and Trump’s first and only scheduled face-off in Philadelphia, and Silver said the poll’s results could be a wake-up call for the Democrat and her supporters.

“Debates are often judged as much by expectations as by the actual performance of the candidates. If the campaign is perceived as a neck-and-neck race for Harris or even as leaning toward Trump, her performance might be viewed in a more favorable light,” he wrote on Sunday.

“And Harris may be better able to avoid the counterproductive risk-aversion bias she demonstrated with the Walz vote. She should campaign as if she were two points behind – because if the Times poll is correct, then she is.”