Gov. Tim Walz of Minnesota said this week that he was “a little surprised” that he and Vice President Kamala Harris lost the presidential election to Donald J. Trump because he had believed the country was ready for the Democratic ticket’s “positive message.”

Sitting on Thursday for his first interviews since the election, Mr. Walz told Minneapolis television stations that he had believed Democrats had the advantage in the election — which Mr. Trump won by capturing all seven battleground states and becoming the first Republican to carry the national popular vote in 20 years.

“It felt like at the rallies, at the things I was going to, the shops I was going in, that the momentum was going our way, and it obviously wasn’t at the end,” Mr. Walz told KSTP-TV. “So yeah, I was a little surprised. I thought we had a positive message, and I thought the country was ready for that.”

Mr. Walz’s admission that he was surprised by Ms. Harris’s defeat was at odds with a more dour assessment of the campaign’s chances by its senior leaders, who appeared late last month on a friendly podcast, “Pod Save America.”

Jen O’Malley Dillon, the campaign chair, and David Plouffe, a senior adviser, each said during an appearance on the podcast that they had not thought Ms. Harris would win heading into Election Day.

“The political atmosphere, the desire for change, all those fundamentals that you’ve spent a lot of time talking about really presented huge challenges for us,” Mr. Plouffe said.