With measles cases popping up around the country, CNN/ORC surveyed Americans on whether vaccinations should be mandatory. Nearly 80 percent said yes, parents should be required to vaccinate their children. And nearly 60 percent said children who are not shouldn’t be allowed to attend public school. Other public polls have shown similar findings.

Whether vaccinating kids should be up to their parents or the government was a hot political topic early this month with probable presidential candidates weighing in. This week’s Loop Congressional Research Service Report pick looks at the federal government’s role in immunization policy.

The federal government can buy and distribute vaccines, as well as keep data and funding research, but is “constrained in its ability to mandate the use of specific vaccines by individuals,” the report says. Requiring immunizations is a states issue.

Our colleague Todd Frankel wrote last month that Mississippi (yes, Mississippi) has the lowest number of unvaccinated children in the country because it has “a strict mandatory vaccination law that lacks the loopholes found in almost every other state.”

States require children enrolling in public schools to be vaccinated, but there are exemptions for any number of reasons, including some states that allow parents to opt out for religious or philosophical reasons.

Gov. Chris Christie (R-N.J.) and Sen. Rand Paul (R-Ky.) made headlines for wavering on whether vaccinations should be mandatory in early February, but in the heated aftermath, most politicians quickly asserted that they should be.

The debate has resurfaced with the resurgence of measles in the United States. Last year, there were more than 600 reported U.S. cases — the highest by far in 20 years. In the first month of 2015 there were 102 cases. As of this week it’s up to 154 cases.

While the annual rate of children getting their measles shots remains above 90 percent, “the increased number of imported measles cases, combined with pockets of unvaccinated individuals, has resulted in a larger number of outbreaks in recent years,” the CRS report says.

Even though the federal government can’t force anyone to vaccinate their kids, it can keep urging folks to do so. U.S. Surgeon General Vivek Murthy, on the White House blog this week, noted the measles outbreak is a serious concern and said: “The most important thing people can do to protect themselves against measles is to get vaccinated.”

Previous Loop CRS Reports of the Week: