Sen. Pat Toomey (R., Penn.) reintroduced a proposal Thursday to cut off funding to the nation's sanctuary cities, whose policies he said "make it harder to stop illegal immigration and keep dangerous criminals off the streets."

The Stop Dangerous Sanctuary Cities Act was initially floated during the last congressional session, but was blocked as part of a whirlwind series of votes on immigration which failed to pass the Senate threshold for cloture. Now, Toomey hopes the bill will get a second hearing.

"It is past time to put an end to dangerous sanctuary city policies," Toomey said. "Sanctuary cities extend a special protection to illegal immigrants even when federal immigration officials identify them as a threat to public safety. This is simply inexcusable, and I urge my colleagues to help pass this commonsense measure."

Under federal law, U.S. immigration enforcement officers can deputize local police to perform certain immigration enforcement functions, as well as ask them to detain deportable immigrants whom the local agency has apprehended for other reasons.

Some cities, and even states, however, prohibit law enforcement officers from coordinating with ICE or CBP, and/or refuse to release information about identified illegal immigrants to federal law enforcement. Municipalities that choose to not enforce federal immigration law are generally called "sanctuary cities" (or, by analogy, sanctuary states).

Proponents of sanctuary cities view federal immigration enforcement as untrustworthy or inhumane, fearing the deportation of long-time residents who happen to also be illegal immigrants. Opponents, meanwhile, raise concerns about cities and states acting to protect even violent, criminal offenders who are illegally resident.

For example, in 2016 the city of Philadelphia refused to comply with a request to turn Juan Ramon Vasquez over to ICE, thanks to the city's sanctuary laws. Vasquez would subsequently be released and sexually assault his girlfriend's five-year-old daughter.

Toomey's bill would push back against the growth in sanctuary cities by moving to deprive any "sanctuary jurisdiction" of certain federal grant funding. This, co-sponsor of the bill Sen. Tom Cotton (R., Ark.) said, was only a fair trade-off for failing to comply with federal law.

"Sanctuary cities keep criminal aliens on our streets, and we will no longer tolerate their willful defiance of our nation's laws," Cotton said. "Public safety must come first. If you're not following the law, you shouldn't get taxpayer dollars, period."

Additionally, the SDSCA seeks to correct court rulings which make local municipalities liable for police action while officers are acting on behalf of DHS. The bill would make the federal government liable in such circumstances, while preserving an individual's right to sue if his constitutional or civil rights are violated.

"Sanctuary cities like San Francisco, Seattle, and New York happily accept federal money, but they are just as eager to ignore our nation's immigration laws," co-sponsor Sen. John N. Kennedy (R., La.) said. "These liberal cities actively impede federal immigration enforcement efforts, which only encourages more illegal immigration."