Joe Biden changes his campaign team leadership….

Former Vice President Joseph R. Biden Jr. is shaking up his campaign leadership just days ahead of the New Hampshire primary, an acknowledgment that his bid for the Democratic presidential nomination is in major trouble after a disastrous fourth-place finish in the Iowa caucuses.

Mr. Biden is giving effective control of the campaign to Anita Dunn, a veteran Democratic operative and top adviser to him.

“She will be working closely with us on campaign strategy and overall coordination on budget and personnel as we build a bigger campaign for the next phase,” according to a campaign email obtained by The New York Times.

But two senior Biden officials said Ms. Dunn is doing more than that — and that she will have final decision-making authority, a decision that came at the behest of the former vice-president. The Biden advisers spoke on the condition of anonymity to discuss internal planning.

The email was sent on Thursday by Greg Schultz, Mr. Biden’s current campaign manager, and a longtime Biden adviser, Steve Ricchetti, who have had differences with each other, reflecting internal generational tensions that have divided the Biden campaign, according to some Democrats close to it.

Mr. Biden’s decision to make such a major change amounts to a recognition that if he does not revive his fortunes in New Hampshire and in the Nevada caucuses on Feb. 22, his so-called firewall in South Carolina — where he is presumed to have strong support from black voters — could crumble and donors will bolt. He acknowledged this week that the result in Iowa was a “gut punch,” a remark his team referenced in the email.

In another indication that Mr. Biden knows he must quickly turn his campaign around, his senior aides reached out this week to Jennifer O’Malley Dillon, a former Obama campaign official who ran Beto O’Rourke’s campaign. The aides asked Ms. O’Malley Dillon to help on their Nevada caucus effort and she agreed to do so in a volunteer capacity, according to a Democrat familiar with the conversation, but she will not join the campaign.

Such shake-ups are common in troubled presidential campaigns — and even before the primary here. In 2008, after being soundly defeated by Barack Obama in Iowa, Hillary Clinton overhauled her staff before winning the New Hampshire primary.