It was kind of funny when whoever posts Instagram photos for Joe Biden celebrated the president’s birthday this week with an image of Biden smiling in front of a cake with a bonfire of candles – presumably 81 – on top of it. “Turns out on your 146th birthday, you run out of space for candles!” the caption reads.

That wasn’t Biden’s only stab this week at poking fun at what might be his most glaring weakness, the widely held perception in opinion polls that he’s too old for another term.

At the annual White House turkey pardon, Biden made clear he was not there at the first pardon, 76 years ago, even though he was alive at the time. But then he seemed to make a generational gaffe when he conflated Beyonce’s tour with Taylor Swift’s, and then called the latter Britney Spears

Rather than praise the birthday joke on Instagram, most commenters have taken the opportunity to criticize his support for Israel. The content of Instagram comments is not a valid measure of any sentiment, but it is true that when people see that content in their feed, they will also see the criticism.

Who knows if the Israel-Hamas war will still be a major top-of-mind issue for American voters when they go to polls in less than a year.

Who knows what will happen with the economy, one of the many areas along with his handling of Israel where polls suggest Biden has weak support, even among Democrats.

Policy tweaks and the natural course of events could change the framework of those storylines.

One thing that won’t change is that Biden will still be the oldest-ever president. While he has poked fun at himself before, the series of jokes on his birthday could be an acknowledgement that his age is an issue to defuse.

Democrats rely on young voters

When Democrats win elections, it is frequently because of turnout by younger voters. In 2022, when Democrats held onto the Senate and only narrowly lost the House, CNN’s Harry Enten wrote they “would have gotten crushed” without younger voters.

So it is with alarm that Democrats must be looking at an NBC News poll out this week that confirms a dramatic drop in Biden’s support among young voters.

Biden is actually narrowly trailing former President Donald Trump among voters ages 18-34 in that NBC poll. Biden won voters ages 18-29 with 60% of the vote in 2020, according to exit polls. A CNN poll released in early November found a similar drop.

It’s important to remember that these current polls are among a pool of all registered voters, which is larger than the subset of people who will actually show up to vote.

Disagreement over Israel

It is Biden’s strong support for Israel that seems to be contributing to a generational wedge between Democrats.

In that NBC poll, only about a third of registered voters approved of his handling of the situation in Israel and only about half of Democrats approved. A majority of Democrats in the poll said Israel had gone too far in its response to the terror attacks by Hamas.

CNN’s John King found more anecdotal evidence in a new report from college campuses in Michigan, which has a large Muslim population. He talked to multiple students who said they supported or volunteered for Biden in 2020 but won’t be doing so this year.

Rather than support Trump, who has talked about reviving his ban on people from mostly Muslim countries traveling to the US, students told King they may not vote at all or may opt for a more liberal third-party candidate.

The writer Franklin Foer wrote a book about Biden, “The Last Politician: Inside Joe Biden’s White House and the Struggle for America’s Future.” Appearing on CNN’s “Inside Politics” on Tuesday, he said perceptions of Israel have changed around Biden.

“I think part of the generational divide is when Biden was a younger person, Zionism and liberalism were much more deeply interconnected and there was a sense that Israel was an underdog nation,” Foer said. The nation of Israel was founded in 1948.

Predating the baby boom

Flip the age issue around and look at Biden’s current difficulty connecting with younger voters not as that of an octogenarian but as someone whose birthday in 1942 predates the post-World War II baby boom, which lasted from 1946 to 1964.

There was a string of four boomer presidents, three of whom (Bill Clinton, George W. Bush and Trump) were all born in 1946, technically the first year of the boom. The fourth, Barack Obama, is technically a boomer as he was born in 1961. There is some gray area between generations, and Obama has written of not really identifying as a baby boomer.

And then, the country went back in time from a president born in 1946 to one born in 1942 when it traded in Trump for Biden.

Incremental changes to the electorate may have important impacts in the coming years, particularly as baby boomers and voters Biden’s age represent an ever-smaller portion of the people voting. CNN’s Ronald Brownstein has written repeatedly about the changing demographics of the country and how that is affecting its politics.

“We are right now at the teetering edge of the influence of the baby boomers,” the University of Florida political scientist Michael McDonald told Brownstein back in May for one such story. “They are just starting to enter those twilight years in their turnout rates, while other [more diverse] groups are maturing. So we are right at that cusp – that critical point of where things are going to start changing.”