CNN’s Julian Zelizer points out that Joe Biden has a Kennedy problem. The nation has had a Kennedy problem since the Depression, in that the United States is supposed to be a nation not given to political dynasties, but the interesting bit about today’s Kennedy problem is that it is beginning to cross party lines.

President Joe Biden might have a Kennedy problem. In recent weeks, Robert Kennedy Jr., the 69-year-old son of the distinguished senator from New York who was tragically assassinated in 1968, announced he is running in the 2024 Democratic presidential primary. Although experts didn’t pay much attention to his candidacy initially, there has been more chatter in recent weeks.

Kennedy, an environmental lawyer turned anti-vaccine conspiracy theorist, is polling between 10 and 20% nationally. And he keeps gaining significant media attention, from a lengthy profile in New York Magazine to his appearance on Joe Rogan’s popular podcast.

There are many reasons Kennedy might cause trouble for Biden. His left-leaning positions on the environment and corporations, coupled with conspiracy theories, many of which are popular on the right, could cause some voters to peel away from Biden.And, of course, there is the Kennedy name — one of the most recognizable and beloved in Democratic politics.

The biggest point RFK Jr. might make, one that Mr. Zelizer doesn’t mention, is Joe Biden’s accelerating mental and physical decline, instead choosing to whistle past this particular graveyard and focus instead on historical precedents for this kind of challenge.

If Kennedy sails to victory, this could cause a fallout reminiscent to what President Lyndon B. Johnson faced in 1968, when Sen. Eugene McCarthy of Minnesota came in a strong second in New Hampshire. McCarthy’s success partly contributed to Johnson’s shock announcement weeks later that he would not, in fact, run for reelection.

McCarthy, of course, did not win that election; Richard Nixon did, although Tricky Dick was assisted in the hustings by the entry of George Wallace as a “Dixiecrat,” which split the Democrat vote. Nixon likely would have won in any case, as he took over 300 electoral votes and won re-election in 1972 in a 49-state landslide. That’s another lesson the Biden people would do well to contemplate. They would also do well to stop ignoring documented facts, as Mr. Zelizer does when he unleashes this spate:

Even with his mediocre approval ratings, Biden is still in a much better position than either Carter or Bush. The president can point to a formidable legislative record. With inflation abating, he can boast about a strong economy where jobs are plentiful and prices have stabilized.

Uh huh.

The odd thing about this whole candidacy, and one that, again, Mr. Zelizer doesn’t really get into, is the amount of crossover appeal that RFK Jr. is getting from the Right, mostly because of his stand on COVID-19 issues. There are a host of reasons why conservatives and libertarians should be vigorously opposing the latest iteration of the Kennedy dynasty:

• He has come out in support of the Green New Deal.
• He supports “assault weapons” bans.
• He is, at best, ambiguous on nuclear energy, claiming support but with lots of qualifications.
• He favors redistribution to address wealth inequality.
• He has said that “climate deniers” should be jailed.

So he’s not just a Biden problem. He’s a problem for the Right as well, and no matter what anyone thinks of his stances on COVID-19 vaccines, he is nothing more than an establishment liberal who may appeal on that one thing but will sell the Right down the river on many others.

Yes, President Biden has a Kennedy problem. But the Right, be they libertarian or conservative, has a Kennedy problem too, and one we should be well aware of. Those on the Right who admire RFK Jr.’s stance on the COVID issue need to take a hard look at his stances on almost everything else.