“Just in case you haven’t been glued to your phone the last few minutes, I want you to hear something from me,” he said in Laconia, N.H. “A little later than we anticipated, but better late than never, official verified caucus results are coming in from the state of Iowa; they’re not complete, but results are in from a majority of precincts and they show our campaign in first place.”

The crowd erupted with cheers and chanted, “President Pete, President Pete!”

Tuesday began a new phase of the Democratic campaign even as the opening vote, the Iowa caucuses, remained unsettled. Candidates who descended on New Hampshire, fresh off overnight flights, aimed to both define their standing in Iowa and jolt their campaigns here before next week’s New Hampshire primary. Meanwhile, their senior aides were effectively backstabbing one another and leaders of the Iowa Democratic Party, signaling a moment of extraordinary tension within the party.

At his first event of the day, former Vice President Joseph R. Biden Jr. tried to put the Iowa contest behind him, while his aides questioned the integrity of the reporting process and swatted at rival campaigns that tried to declare victory before the official results.

Those initial results indicated a distant fourth-place finish for Mr. Biden with nearly three quarters of the vote in — pulling in 15.5 percent. Such a result would represent a major blow to a former vice president who had invested substantial time and resources in the state despite his team’s efforts to play down expectations there.

“Folks, God, it’s good to be in New Hampshire,” Mr. Biden said, laughing. “It really is. I really mean it. You have no idea how happy we were to be heading to New Hampshire, to Nashua.”