President Biden is promising COVID-19 vaccines will be available to all Americans by the end of July — and a Quinnipiac poll finds three-quarters of Americans expect him to pull it off.  If he fails, the coronavirus could start to haunt the new president just like it did his predecessor.

Why it matters: Biden’s presidency is built on the notion of restoring competence — and confidence — in government. So, he'll need the huge infusion of cash from his virus relief bill — and heroics by drugmakers and distributors — to carry out mass vaccinations.

• He'll need to hit or near this mark if America is truly going to return to normal for the fall school season. 
• And he'll need to hit or near this mark to make good on his belief that life will return to "approaching normalcy" by Christmas.

Here's the big asterisk: Administration officials say the U.S. will have enough vaccine (600 million doses) to give everyone two shots by July 29. But they know not everyone will take it.

• "[T]he reluctant and the hesitant will drag this out all fall," a top official tells me.
• That's partly because of the historically rooted suspicion of vaccines among minorities, and many largely poor or isolated populations.

Here are things that could prevent Biden from hitting his goals:

• Resistance from Senate Republican Leader Mitch McConnell.
• A violent new wave and strain of the virus. This could result from people getting sick of COVID isolation, and dropping their guard with the advent of warm weather.
• An inability or reluctance of some states to find the right balance of COVID restrictions.
• A foreign policy crisis that occupies Biden and his team.
• Conservative media hammering his efforts on a nightly basis, adding to the vaccine reluctance and suspicion of Democratic plans.
• The economy fails to grow, and the stock market stutters and slumps.