The Biden administration has moved up its deadline for all Americans to become eligible to receive a coronavirus vaccine, announcing Tuesday that states will begin vaccinating all adults on April 19, if not before.

The announcement formalizes a timeline that was already in place in nearly every state, allowing President Biden to accelerate his previous deadline of May 1 for all adults to be able to register for an appointment. The White House said the uniform eligibility date should clear up confusion about who is eligible and when. “No more confusing rules; no more confusing restrictions,” Biden said in formal remarks Tuesday, as he mixed optimism about vaccines with somber warnings about the spread of new virus variants and a rise in cases.

Biden also announced Tuesday that 150 million coronavirus vaccine shots have now been administered. He pleaded with Americans to get their shots and continue to take precautions, adding that a goal of small family gatherings for the Fourth of July remains realistic.

While millions of Americans are getting vaccinated, new coronavirus infections are rising again, as variants of the virus have spread and some states and businesses have begun to relax restrictions.  “The virus is spreading because we have too many people who see the end in sight and think they’re at the finish line already,” Biden said. “Let me be deadly earnest with you: We aren’t at the finish line,” Biden said at the White House. “We still have a lot of work to do. We’re in a life-and-death race against the virus.”

Both Biden and Vice President Harris visited vaccination sites earlier Tuesday as the administration seeks to keep a focus on staying ahead of the pandemic. “You’re doing the right thing,” Biden told people receiving vaccines at a temporary clinic in Alexandria, Va.

The accelerated eligibility deadline was made possible by the greater availability of vaccines, as well as many states’ decisions to open the process to all adults rather than select groups prioritized by age, vulnerability or occupation.

The administration’s previous goal was to make 90 percent of all adults eligible by April 19, so the new marker is a modest change. It does not ensure that all eligible adults will in fact be given a shot by that date, only that they will be allowed to put their name on a list for whenever an appointment becomes available.

“By April 19, all adult Americans will be eligible to get the vaccine. That doesn’t mean they will get it that day; it means they can join the line that day if they have not already done that,” White House press secretary Jen Psaki said.

While large parts of the country still have waiting lists and limited supplies of vaccine doses, the development is a sign that the ambitious goal of mass vaccination in early 2021, once a seemingly remote prospect, probably will be met. The larger goal is sufficient immunity among Americans to end the spread of the virus and stop a pandemic that has raged for more than a year, claiming the lives of more than 557,000 Americans and disrupting daily life, businesses, schools and more.

When it comes to the virus, Biden has made a practice of announcing goals that turn out to be relatively easy to meet, and then trumpeting his success in surpassing them.

In announcing — and revising — a series of numerical targets, Biden has sought to create a sense that the nation is speeding past impressive mileposts. That could generate a feeling of momentum in defeating the virus and potentially help Biden politically.

But if the virus has another resurgence, Biden risks being attacked for premature celebration, and he repeatedly tempered his comments Tuesday with reminders that victory is not yet in hand.

More than 4 million people in the United States received a coronavirus vaccine shot on Saturday — the highest one-day total since the shots began rolling out in December — amid a rising caseload and increase in hospitalizations.

A record-low number of U.S. adults are worried about contracting the virus, a new Gallup poll found — 35 percent, down 14 percentage points from February.