For months, battered by President Biden’s dismal 2024 re-election polls, Democrats have been undergoing a kind of collective nervous breakdown over Mr. Biden’s re-election prospects against Donald Trump.

Following Mr. Trump’s victory in New Hampshire and with the unofficial start of the general election campaign, there is no reason for the Biden team to panic. Polls at this stage of the race are almost always a referendum on the incumbent instead of a clear choice. Still, the president’s bad polls and a stubbornly low approval rating are, or should be, more than just grist for Mr. Biden’s critics. They’re proof that his campaign needs to overhaul its message.

Joe Biden has yet to explain clearly why he’s running for a second term. I’ve reached this conclusion after speaking with more than a dozen ex-presidential campaign managers and top political strategists — indeed, I spent two years writing a book about the Biden presidency.

To articulate his vision for America, and his case for re-election, the president — whom, I should note, I am rooting for — must campaign in both poetry and prose. The poetry will be in his pledge to preserve the integrity of the Constitution and safeguard democracy, and the prose in his promise to deliver on kitchen table issues where many voters believe he’s fallen short.

As the incumbent, Mr. Biden cannot run as an outsider. But he has a strong populist case to make for a future in which ordinary Americans, and the ideals embodied in our Constitution, can prosper. This case would offer a stark and optimistic contrast to Mr. Trump, whose only allegiance is to himself and to retribution for his imagined grievances.

A recovery narrative

The top issue for many voters is the economy, and to overcome Americans’ gloomy outlook on this front, Mr. Biden needs a new narrative.