Some states are expanding vaccine eligibility partially because of a troubling reason: Not enough people want to get vaccinated.

What we're watching: Vaccine supplies are still limited, but they're already outpacing demand in some parts of the country, especially rural areas. And that could be a bad sign for the future.

Where it stands: 14 states have made all adults eligible to receive a coronavirus vaccine, and the vast majority have said they will do so by or before President Biden's May 1 goal.

• Many local governments have also broadened their own eligibility criteria, and demand can vary significantly within states.
• Those states and cities generally have below-average vaccine demand compared to the rest of the country, and officials say they're letting more people in simply because they weren't getting enough sign-ups.

What they're saying: Vaccine appointments "are not being snapped up in 10 minutes like they were a month ago,” Nirav Shah, director of Maine’s Center for Disease Control and Prevention and the president of the Association of State and Territorial Health Officials, told the Washington Post.

• “This I take as the very earliest sign that we are shifting from urgency to hesitancy,” he added.
• "One of the reasons that we are pushing forward on expanding eligibility is because our uptake has been lower than expected," Tennessee's state health commissioner, Lisa Piercey, recently told News 5.
• Last week, the Illinois department of health said local health departments that have seen waning demand can begin vaccinating anyone 16 and older, the Chicago Tribune reports. Demand is still high in Chicago, but not in other parts of the state.

The big picture: Republicans have emerged as the most vaccine resistant demographic group in the U.S., followed by white evangelical Christians and rural residents.

Details: Among U.S. adults who haven't yet received a coronavirus vaccine, about half say they definitely plan to get one, according to the latest Census Bureau Household Pulse Survey.

• The share of people saying they definitely plan to get the vaccine is lowest in ruby-red states like Mississippi, Wyoming, North Dakota and Montana.
• In Mississippi, for example, nearly 1 in 5 unvaccinated people say they definitely don't want a vaccine. In North Dakota, more than a third said the same — significantly more than said they would definitely get vaccinated.
• In contrast, states with the highest levels of vaccine enthusiasm among the unvaccinated tend to be blue, including the District of Columbia, Vermont, Washington and Massachusetts.