Then perhaps the only thing that helps is humor, as Ronald Reagan did. Even the then oldest incumbent president in US history, who left office in 1989 at the age of 77, was repeatedly interpreted as a sore point. The sprightly Republican was not able to withdraw from the discussion, but with jovial self-mockery he often took away the conjured fire emergency - and possibly even turned an election campaign that he thought was lost in his favor.

Reagan's reply in a television debate against Walter Mondale, in which he assured his opponent - after being asked about his age of 73 at the time - that he would not exploit his opponent's "youth and inexperience" for political purposes is now considered legendary. Even Mondale, 56, had to laugh heartily. Reagan's unfortunate poll numbers skyrocketed, and the Democrats were spectacularly duped in the 1984 presidential election.

Now Joe Biden holds the record, and the 46th President of the United States - who is celebrating his 80th birthday today - is trying to parry the repeated finger pointing to his advanced age with punch lines. "Once in a while I make a mistake," Biden joked during an appearance in May, "well, once a speech."

This may not be as effective as Reagan's, who calculated his age nicely here and put it in relation to antiquity there, but shows a certain composure and conviction of the pragmatist Bidens, who understands the results as a resilient counterargument.

"Look at me, Mr. President," he said in August 2020 to Donald Trump, who then and now questioned his fitness - and in the years that followed watched Biden push through several huge investment packages, the Trump swept up the shards he left behind and most recently achieved respectable success in the congressional elections.

Unlike Reagan, however, Biden will not succeed in avoiding the discussion about his age - the Republicans, who work with remarkable zeal on the allegedly "dodder" (Ron DeSantis) and "diminished" (Marco Rubio) president, should already know how to prevent this and pounce on every rhetorical lapse that Biden regularly throws at them.

Even among Democrats, there are many who are unsure whether Biden is the appropriate frontrunner in the 2024 White House race. His poll numbers remain lousy for all his accomplishments, but given his lackluster popularity ratings, three-quarters (75 percent) of the electorate in a CNN poll in July favored a candidate other than Biden, prompting many Democrats to avoid joint appearances in the midterms the president.

And then there's age. Should Biden actually aim for a second term in office, which the usual health check for US presidents already attests to as having a "stiff gait" and general "wear and tear", he would leave office at the age of 86. It would again be a first in US history - which is apparently associated with great uncertainty,

While 71 percent of Democratic voters thought he was "mentally fit and able to deal with challenges," according to a recent Reuters and Ipsos poll, 46 percent questioned whether he would be up to the challenge of running for office in 2024. The New York Times even spoke to ten experts on aging "to paint a picture of what the next six years might look like for a person the president's age," the newspaper writes.

And last but not least, the "Wall Street Journal" asked itself in an opinion piece whether an elderly Biden could still face aggressive autocrats like China's President Xi Jinping with enough bite . The answer came from the paper between the lines: "If I were only 80 years old," the newspaper quoted former US President Jimmy Carter at the age of 94, "I don't think I could take on the tasks that I do experienced as President."

Biden has promised a decision at the beginning of the year as to whether he will run again. "My intention is to run again," he said. "But I have great respect for fate. And this is ultimately a family decision."

But time is of the essence, Donald Trump's hasty advance and Ron DeSantis' meaningful wait and see put the Democrats under pressure to choose their candidates - and sometimes worried: "I wish he were 30 years younger, 20 years younger, 10 years younger. But it is what it is," Democratic Rep. David Trone, 67, told CNN. When asked if Biden was the right candidate for 2024, Trone said, "I think it would be better if we had someone with a little more momentum." But if Biden runs again, he will support him – other Democrats put it in a similarly reserved way.

If not Joe, then who? There are some very high-profile candidates in the starting blocks (which you can see here), but none of them want to run against Biden. The party is waiting for its president, who, among other things, wants to celebrate his milestone birthday with a brunch with the family, as his spokeswoman said, and probably doesn't want to acknowledge the milestone himself.

"Someone said my birthday is coming up," he said recently. "And I said, 'No, that has to be someone else'." When asked what 80-year-old Biden would say to 50-year-old Biden, he replied, "That I'm still 50!" And added that he "couldn't even say that number", 80.

Gregory Magarian, a constitutional lawyer at Washington University in St. Louis, says Biden is now considering the candidate question. "But the reality is he has to think about what his energy and ability will be like six years from now if he were at the end of a second term." The job requires a high level of energy and perspicacity. "Being US President is certainly one of the toughest jobs in the world." And certainly also at 80.

Incidentally, Reagan celebrated his birthday with a big reception at the Beverly Hilton Hotel, as the "Los Angeles Times" reported at the time, and is said to have blown out the candles on his birthday cake so enthusiastically that glaze flew onto the lapel of his tuxedo. "If only I had thought about such things years ago, I would have been twice as good at pictures," he said. Reagan said he didn't want to give a speech. "I'm guessing you've heard a thing or two over the years anyway."

Sources: Time, Politico, Los Angeles Times, AP News, New York Post, ABC News, FiveThirtyEight, CNN, Reuters, New York Times, Wall Street Journal, Washington Post," White House, with footage from the DPA news agency