WASHINGTON, D.C. - U.S. Sen. Pat Toomey is launching a new strategy for curbing illegal immigration and ending sanctuary cities.

During a news conference Wednesday morning, the Senator outlined his plan that would withhold federal grant funding for sanctuary cities unless they comply with federal law. Sanctuary cities are areas that forbid local law enforcement from working with federal authorities when an undocumented immigrant is arrested for a crime.

Philadelphia and San Francisco are among the most well-known sanctuary cities in the country. Locally, the City of Ithaca, N.Y. and Bradford Co., Pa. have similar policies, according to the Center for Immigration Studies.

“My hope is that cities will take that as an incentive to exercise some common sense and resume cooperation with federal law enforcement,” Toomey said.

The bill would provide a safe harbor for cities that do not provide names of undocumented immigrants who act as witnesses or victims of a crime.