After self-inflicted wounds from his boasts over decades-old work with segregationist senators and a desultory debate performance, Joe Biden is resetting his campaign to confront his Democratic primary rivals.

The former vice president's strategy, previewed Wednesday night at a Detroit fundraiser, marks a dramatic shift from the front-runner's version of a Rose Garden strategy, which was heavy on campaign fundraising and light on taking on his two dozen primary rivals. He is now pledging to attack his rivals head-on, abandoning his nonaggression campaign promise made in May.

His poll numbers plummeted after a near-disastrous debate performance in Miami last month, when he wilted under an attack from Sen. Kamala Harris of California. He will now face Harris again in a Detroit debate next Wednesday, along with Sen. Cory Booker of New Jersey, with whom he has tangled this week.

Biden, 76, has overhauled his stump speech to focus on more than nostalgia for the president he served under, Barack Obama. The 36-year Senate veteran is now outlining what his presidency would look like, should he win the Democratic nomination and beat President Trump in fall 2020.

Democrats told the Washington Examiner it was plain that Biden was overhauling his approach in an attempt to cling onto his dwindling lead.

He is "reconfiguring" his campaign, according to Rhode Island Democratic Sen. Jack Reed, who has praised Biden without formally endorsing him. He's changing "approaches based on the previous debates."

Democratic consultant Brad Bannon, who is unaffiliated in the 2020 campaign, said Biden was scared by the last debate. "I think the pummeling he took at the the first round of debates shocked him and the campaign. I think he and his campaign weren't ready to go," Bannon told the Washington Examiner. "There's a significant strategy change here. The reality is he's in a very competitive race after losing support. It's a drastic change. Things have been going downhill for his campaign since he announced."

Sen. Dick Durbin of Illinois, the Democratic whip, who has endorsed no 2020 candidate, said: "He's the front-runner and he naively believed that he wouldn't be a target and he was and will be as long as he's the front-runner," "So now he's going to answer. He tried to be nice and it didn't work. So now he's going to be less polite in his words."

At the Detroit fundraiser Wednesday night, Biden told the well-heeled crowd, “I’m not going to be as polite this time.” He then laid into Harris: "Because this is the same person who asked me to come to California and nominate her in her convention.”

Much has changed since the June 27 primary debate, when California Sen. Kamala Harris took the former vice president to task for opposing busing designed to end racial segregation in schools, and declared that she had been a victim at age 6, saying "I was that little girl." She later pressed Biden on his remarks touting his collaborative working relationship with known segregationists former Sens. James O. Eastland of Mississippi and Herman Talmadge of Georgia in the Senate during the 1970s.

The consequences of Biden's debate performance were felt immediately, with polls showing his support hemorrhaging among Democratic voters. A MorningConsult/FiveThirtyEight poll found his numbers dropped 10 points just one day after.

Since then, he has taken a different approach on the campaign trail than his previously laid-back efforts. His campaign stops in Nevada last weekend were billed by his team as a nationwide "Day of Action," aimed at energizing existing Biden supporters and winning converts to the cause.

Rather than just talk about the rising costs of prescription drugs, Biden channeled his inner populist and declared in Las Vegas that some pharmaceutical executives should be "in prison" for their role in the opioid crisis.

On the same trip, Biden directly challenged opponents such as Harris and Sen. Bernie Sanders of Vermont on issues such as healthcare. He called their support for Medicare for All, billed by Sanders as universal coverage, as a betrayal of the Affordable Care Act, the Obama administration's signature domestic achievement.

“There’s a lot of people, including in our party as well, who want to get rid of Obamacare,” Biden said.

In a press gaggle that day, Biden knocked Harris for her ambiguity on the issue. “Look, I think that I have no doubt about the intention and the fervor and the sincerity of Bernie, Elizabeth. Kamala, I'm not sure, I think she says she's for Bernie's plan.” This week, he called Harris' promise not to raise taxes on the middle class as something from a "fantasy world."

Senate Democrats remarked on the noticeable strategy change among Biden's campaign.

Biden this week also attacked Booker, bashing the New Jersey senator over the city of Newark's policing policies when he was mayor. "Today, Booker called Biden the 'architect of mass incarceration.' The absurdity of this attack is obvious," Biden's deputy campaign manager Kate Bedingfield wrote in an email. "It is Senator Booker, in fact, who has some hard questions to answer about his role in the criminal justice system."

Despite the campaign's strategic change, internal structural problems remain. During his tour of Las Vegas, Biden's advisers often didn't know his location or when he'd arrive at his various campaign stops.

"What, am I supposed to know his schedule?" senior staffer Harvey Greene joked to the Washington Examiner when asked about the timing of of a press conference after Biden promised reporters he'd take questions at the conclusion of an event.

Following an event at a phone bank, Biden insisted on meeting with almost every supporter in attendance, devoting over an hour to shaking hands and exchanging pleasantries. That sparked concerned looks from his campaign staff who worried about getting him to his next event before its scheduled conclusion.

When it finally came time to speak to reporters, his traveling press secretary repeatedly tried cutting him off, to no avail.

Last month, the Washington Examiner reported on internal frustrations felt by Biden's campaign staffers who felt their candidate was impossible to advise. At one tour of New Hampshire that month, Biden turned up an hour late to a local diner stop because a campaign staffer said he was busy catching up on that day's Morning Joe show on MSNBC.