The White House on Monday suggested former president Donald Trump shouldn't be waiting for an "engraved invitation" to join the public campaign encouraging Americans to take Covid-19 vaccines.
President Joe Biden's press secretary, Jen Psaki, noted that all other living former presidents, including Democrat Barack Obama and Republican George W. Bush, have delivered public service announcements.
Trump, by contrast, has kept largely quiet since leaving the White House and moving to his luxury resort in Florida.
"Every other living president... has participated in public campaigns. They did not need an engraved invitation to do so. So he may decide he should do that. If so, great," Psaki said.
"If former president Trump woke tomorrow and wanted to be more vocal about the safety and efficacy of the vaccine, certainly we support that."
The United States is on track to produce far more vaccine than it is likely to need for the entire population. And with logistical problems gradually being ironed out, experts expect the biggest hold up to mass vaccination will be skepticism among parts of the population.
Polls show that Republican men, who are overwhelmingly supporters of Trump and his "Make America Great Again" or MAGA platform, are leading that resistance to getting vaccinated.
Asked about the phenomenon, Biden said that Trump's opinion on vaccines mattered less than advice from local medical and community leaders.
"I discussed it with my team and they say the thing that has more impact than anything Trump would say to the MAGA folks is what the local doctor, what the preachers, what the local people in the community say," he told reporters.
"So I urge, I urge all local docs, and ministers, and priests to talk about why, why it's important to get that vaccine, and even after that -- until everyone is in fact vaccinated."
Trump and his wife Melania got their own vaccines before leaving the White House in January, an advisor said. Unlike Biden and other current officials who got their shots live on television, Trump in a highly unusual move kept his own vaccination private.