Democrats Taste Victory in November. But Are They Too Confident?

Democrats were giddy. After months of hand-wringing and pessimism before President Biden stepped aside, they were finally excited again.

Among the delegates inside the United Center, there was one overriding thought.

We can’t lose.

“She’s going to win in a landslide,” said Aleksy Federov, 36, a delegate from Washington State who recently became a citizen. Wearing a white blinking cowboy hat, Mr. Federov cited the “energy in the air,” adding, “It’s generational change in politics.”

“And there is Kamala Harris,” he said Thursday afternoon, hours before the vice president formally accepted the Democratic nomination for president at the convention in Chicago. “She brings the joy to the people.”

But in a series of high-profile admonitions during the four-day convention, several Democratic Party elders issued stern warnings for anyone believing the happy talk that Vice President Kamala Harris and Gov. Tim Walz of Minnesota are on a glide path to the White House.

“Never underestimate your adversary,” said former President Bill Clinton, whose wife knows all too well the bitter sting of losing to former President Donald J. Trump.