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Good evening. Here’s the latest at the end of Tuesday.

1. President Biden announced his re-election campaign.

In a video message posted this morning, Biden formally kicked off his 2024 presidential campaign, arguing that American democracy still faces a profound threat from former President Donald Trump as he set up the possibility of a climactic rematch between the two next year.

In the video — which opens with images of a mob of Trump supporters storming the Capitol on Jan. 6, 2021 — the president says that the “fight for our democracy” has “been the work of my first term.” But, he says, that work is incomplete while Trump mounts a comeback campaign, which Biden suggests would endanger fundamental rights.

In a speech later in the day to a labor group in Washington, Biden focused more on bread-and-butter issues, boasting of his record of creating jobs and financing new roads and bridges.

While the 2024 contest may be a rematch — Trump is for now the Republican front-runner — the landscape for Biden looks different. Nearly seven in 10 Americans believe the country is on the “wrong track,” more than half of Democrats don’t want him to run for re-election, and, at 80 years old, he is already the oldest president in American history. And yet, Democratic officials firmly believe that he is better positioned than any potential rival.

Early poll numbers, which should be taken with a grain of salt, show a tight race no matter the potential candidates. But history may be on Biden’s side: Only four presidents have lost re-election bids in the past century.

In related news, Biden tapped Julie Chávez Rodríguez, the highest-ranking Latina in the White House and a granddaughter of Cesar Chávez, to run his campaign.

2. The exits of Tucker Carlson and Don Lemon marked the end of an era in cable news.

The two hosts were on very different networks and did very different things to draw very different ratings. Carlson was perhaps the biggest star on all of cable news and helped shape conservative thought with inflammatory monologues on immigrants, Black civil rights activists, vaccines and national identity. Lemon was known for his anti-Trump broadsides, although they were tame in comparison.

However, both were products of the Trump years who often made headlines themselves by giving their audiences generous helpings of indignation and outrage. Their almost simultaneous ousters yesterday represented at least a temporary pulling back from the excesses of the media coverage spawned by the Trump election, presidency and post-presidency.

For more: Little is still known about what exactly led Fox to dismiss Carlson, but his history of controversy and potential legal issues may have prompted the Murdochs to swing the ax.

3. Harry Belafonte, the barrier-breaking singer, actor and activist, died at 96.

In the 1950s, when segregation was still widespread and Black faces were still a rarity on screens large and small, Belafonte stormed the pop charts with his highly personal brand of folk music. He almost single-handedly ignited a craze for Caribbean music with hit records like “Day-O (The Banana Boat Song)” and “Jamaica Farewell.” For a few years, no one in music — Black or white — was bigger.

From the late 1950s on, however, civil rights, not entertainment, were his focus. He put up much of the seed money to help start the Student Nonviolent Coordinating Committee, provided money to help bail Martin Luther King Jr. and other activists out of jail and became a lifelong supporter of King’s quest for racial equality.

4. Ukraine’s spring offensive comes with immense stakes for the future of the war.

Ukraine is preparing to launch a counteroffensive against Russian forces as early as next month, American officials say. The stakes are incredibly high: Without a decisive victory, Western support for Ukraine could weaken, and Kyiv could come under increasing pressure to enter into serious negotiations to end or freeze the conflict.

Ukrainian officials have said their goal is to break through dug-in Russian defenses and push Russia’s army to collapse. But American officials believe it is unlikely the offensive will drastically shift momentum in Ukraine’s favor.

5. A Japanese company lost contact with its moon lander.

Ispace had aimed to complete the first moon landing by a private company, but it lost contact today with its small robotic spacecraft — a signal that it may have crashed into the lunar surface.

While the lunar landing attempt appears unsuccessful, Ispace won’t be the last company to try. Two more landers, both made by U.S. companies and funded by NASA, are scheduled to be launched to the moon this year.

6. The places most at risk from heat waves might be those that haven’t experienced them.

Global warming is making dangerously hot weather more common on every continent. And while we’ve seen its effect on cities around the Equator, where midday outdoor work has become dangerous, a new study argues that it’s the regions of the world that haven’t yet experienced an off-the-charts heat wave that we should worry about.

These areas — which include economically developed places like Germany and the Netherlands — are less prepared, the scientists argue, because they have never had to adapt to living in an extended hot spell.

7. Researchers found that many melatonin gummies are mislabeled.

When a team of researchers analyzed 25 brands of melatonin gummy products, commonly used as sleep aids, they found that 22 contained different amounts of the substance than advertised. One of the supplements contained nearly 350 percent of the amount the label claimed, while another appeared to have none at all.

For people taking less melatonin than they believed, the results may be lackluster. Those taking more are more likely to experience side effects like grogginess the next morning, a specialist said.

Speaking of mornings, we asked experts about the secrets of a healthy breakfast.

8. The American Museum of Natural History’s new star attraction is ants.

When the Richard Gilder Center for Science opens to the public in New York City next month, visitors will be able to experience the sophisticated lives of leafcutter ants. About 500,000 of them will live in an enormous new exhibit, functioning as a single superorganism and harvesting leaves to sustain fungal gardens.

The museum’s new wing — with an atrium designed like a towering canyon — is a marvel to stand inside, our architecture critic writes. It seems destined to become a colossal attraction, especially for children.

For more: Behind the new exhibits at the museum’s insectarium is Jessica Ware, an entomologist who is also working to attract more people of color to her field.

10. And finally, when dating apps failed, one man turned to a time-honored method.

Alex Miller, a software engineer from Brooklyn, was a lot like other single millennials: burned out from anxiety-inducing dating apps and in need of a date (to his brother’s wedding). But unlike his peers, he used a method that has been around since at least the 1700s: the personal ad.

Miller taped up his ad — which called for someone who likes “pleasing Jewish grandmas” — around his neighborhood and managed to generate more interest than he expected. At least 20 people reached out, including a couple looking to be a plus-two and a Texas woman who got his number from a friend in New York.

Have an old-school night.

Brent Lewis compiled photos for this briefing.

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