People participate in a pro-refugee protest organized by Americans for Refugees and Immigrants in Seattle on Nov. 28. (Reuters/Jason Redmond)

More than half of the nation’s governors say they will not accept Syrian refugees in their states, but they may have little choice.

States cannot pick and choose which refugees to take in, federal officials with the Health and Human Services Department’s Office of Refugee Resettlement warned in a letter sent out last week. If they deny services to any group of refugees, states may risk losing resettlement funding altogether.

“States that continue to use ORR funding must ensure that assistance and services are delivered without regard to race, religion, nationality, sex, or political opinion,” ORR Director Robert Carey wrote. “States may not deny ORR-funded benefits and services to refugees based on a refugee’s country of origin or religious affiliation.”

[Anne Frank and her family were also denied entry as refugees to the U.S.]

The letter, dated Nov. 25, was sent out last week to refugee resettlement programs in 49 states and the District. Wyoming does not have a resettlement program.

Thirty state governors have promised to block Syrian refugees from settling within their borders since Islamic terrorists attacked Paris on Nov. 13. Opponents of taking in the refugees cite fears that the federal government’s screening process may fail to weed out extremists, a concern the HHS letter addresses.

“Syrian refugees are subject to even more precautions than other refugees,” the letter notes. “It is the most robust screening process for any category of individuals seeking admissions into the United States.”

Nonetheless, controversy has swirled around the resettlement of Syrian refugees in the half-month since the Paris attacks.

Within days, Republican presidential hopeful Donald Trump accused President Obama of sending Syrian refugees to Republican states. One by one, governors, attorneys general and other state lawmakers weighed in, promising to bar all new Syrian refugees, calling for improved federal screening and proposing bills to address the issue.

Two weeks ago, the Republican-controlled House passed a bill that would require the FBI director to certify the background investigation of each Syrian or Iraqi refugee admitted to the United States.

[It’s not just Donald Trump: Half of Republicans share his views on immigrants and refugees]

Generally, though, experts say refugees pose little threat to the United States.

“The threat to the U.S. homeland from refugees has been relatively low. Almost none of the major terrorist plots since 9/11 have involved refugees,” Seth Jones, director of the International Security and Defense Policy Center at the RAND Corporation, testified to Congress in June. “Even in those cases where refugees were arrested on terrorism-related charges, years and even decades often transpired between their entry into the United States and their involvement in terrorism. In most instances, a would-be terrorist’s refugee status had little or nothing to do with their radicalization and shift to terrorism.”

But the raging debate may all be for naught. In the end, states may have little ability to control the flow of refugees.

Tennessee Attorney General Herbert Slatery released a legal opinion on Monday at the request of a state Democrat, in which he noted that the state would violate federal law by setting rules on refugee placement.

[Fact Checker: The viral claim that ‘not one’ refugee resettled since 9/11 has been ‘arrested on domestic terrorism charges’]

Professors Pratheepan Gulasekaram and Karthick Ramakrishnan offered up a similar analysis for The Washington Post last month.

“Both the Constitution and federal law prohibit states from picking and choosing among refugees, as they are proposing to do here by discriminating against Syrians,” the pair wrote. “Indeed, multiple Supreme Court decisions dating back to the late 1800s make it clear that states are constitutionally prohibited from discriminating on the basis of national origin or denying the opportunity to live or seek work to immigrants once the federal government has seen fit to admit them.”

Related stories:

The law is clear: States cannot reject Syrian refugees

How many Syrian and Iraqi refugees were settled in each state since 2012, in 3 maps

The viral claim that ‘not one’ refugee resettled since 9/11 has been ‘arrested on domestic terrorism charges’