WASHINGTON — President Biden implored Americans on Thursday to “knock on doors and talk to friends and neighbors” about getting vaccinated, as the White House opened a campaign-like blitz to persuade people around the country to get their shots.

Mr. Biden’s speech, in North Carolina, came as the government is shifting its strategy from mass vaccination sites to a more localized effort — deploying top officials to local communities, with an eye toward younger Americans who have not had the access or are reluctant to get vaccinated.

“This can be among the most important things you do,” Mr. Biden said, before reminding the crowd of dozens of canvassers and attendees at Green Road Community Center in Raleigh that more than 600,000 Americans have died from Covid-19.

The White House has sent other big names out on the road recently, as well. The first lady, Jill Biden, visited vaccination sites in Florida on Thursday and planned to travel to at least five states between this week and July 4. (It is a traveling schedule that, at this point, is busier than her husband’s.)

Dr. Anthony S. Fauci knocked on doors last weekend in a predominantly African American neighborhood in Washington, and Douglas Emhoff, Vice President Kamala Harris’s husband, visited a barbershop in Chicago this week to learn why residents were turning away shots.

The message has been clear: Vaccines are available and beneficial, with mobile vaccination units in many neighborhoods and extended hours at pharmacies. On Thursday, Mr. Biden also encouraged those in Raleigh to take advantage of free trips by ride-hailing companies to vaccination sites.

The flurry of travel reflects the sense of urgency as the pace of vaccinations slows and the White House acknowledges that the country will most likely fall short of Mr. Biden’s goal of partially inoculating 70 percent of American adults by July 4.

Health officials also warn of the rising danger of the Delta variant, a more contagious version of the coronavirus first identified in India. Dr. Fauci said this week that the variant accounted for an estimated 20 percent of new infections.

“You know there’s going to be others, as well,” Mr. Biden said of the variant. “You know it’s going to happen. We got to get our young people vaccinated. So talk to those moms when you knock on the doors.”

North Carolina exemplifies many of the challenges the Biden administration is facing. Just 45 percent of the state is partially vaccinated, and 7 percent of those between ages 18 and 24 have received at least one shot, according to the state’s Department of Health and Human Services.

The White House is hoping 78-year-old Mr. Biden can help convince them.

“With age comes wisdom, and we’ve certainly seen that here with their rollout of the vaccine in the United States,” said Dr. David Wohl, the medical director of vaccination clinics at the University of North Carolina, Chapel Hill.

To speed vaccinations, he said, Mr. Biden would need to treat the outreach “like a political campaign.”

“We have a tall order in front of us,” Dr. Wohl said. “I think he’s walking the walk. I think he’s saying you’re not impervious to this virus. You can get sick.”

Dr. Carlos del Rio, a professor of medicine and an infectious disease expert at Emory University in Atlanta, said the administration should stick to relying on localities rather than top government officials.

“I don’t think he’s a good messenger,” Dr. del Rio said. “I don’t want the government to tell me to get a vaccine. I want my doctor. I want the fireman who goes to church with me. You need trusted messengers.”

Dr. del Rio said he had been working with the African American community in Atlanta, where preachers have been instrumental in persuading their congregants to get vaccinated.

Experts know that one way to address vaccine hesitancy is for individual doctors to recommend vaccination, or offer the vaccine to patients who may come in for other reasons.

Mr. Biden also used his speech to acknowledge the distrust in the Black community about the vaccine.

When coronavirus vaccines were introduced in the past year, researchers tracked a rise in social media posts about the infamous Tuskegee study in which health officials followed African American men infected with syphilis but did not treat them.

Mr. Biden noted that people of color received more than half of the roughly six million shots administered at federally run mass vaccination sites.

“The more we close the racial gap in vaccinations, the more lives we can save,” he said.

The push for vaccinations has also run into reluctance among many conservatives, who cite a variety of worries including religious concerns and distrust of the government.

On Thursday, Mr. Biden’s focus was on young people.

Just over one-third of adults ages 18 to 39 reported being vaccinated, according to a report released on Monday by the Centers for Disease Control and Prevention. Those who were 24 or younger, as well as non-Hispanic Black people and those with lower incomes, less education and no health insurance, had the lowest reported vaccination rates and expressed the least interest in getting vaccinated, the report said.

Mr. Biden made clear on Thursday that he would need the help of those listening to him in the community center.

“I have faith in your generation,” he said.

He is also relying on his closest advisers, including the first lady, who visited a drive-through vaccination site in Kissimmee, Fla., on Thursday.

A line of cars crawled through the parking lot to the mobile clinic, where Dr. Biden and Dr. Fauci greeted health care workers and those who were waiting for shots.

“See how easy that was?” Dr. Biden said after a driver received a jab and a vaccine card.

Katie Rogers and Sheryl Gay Stolberg contributed reporting.