From a story on politico.com by Charlie Mahtesian headlined “Biden’s Toughest Republican Challenger”:

As President Joe Biden kicks off his reelection bid, he begins from a position of weakness: The president has been underwater in the polls for close to two years. His approval ratings dropped under 50 percent around the time of the chaotic Afghanistan pullout in August 2021, and never truly recovered.

Only three post-war presidents — Jimmy Carter, Ronald Reagan and Donald Trump — were in a worse polling spot at this point in their reelection campaigns. And two of those three lost.