(AP) — Attorney General Jeff Sessions will travel to California to make a major announcement about sanctuary policies that limit local and state cooperation with federal immigration authorities.

Sessions is expected to speak Wednesday to law enforcement officials at an annual gathering of the California Peace Officers’ Association in Sacramento.

Trump administration officials have promised to crack down on policies that keep local law enforcement from advising federal agents when they release immigrants living in the country illegally.

The administration has heavily criticized California, home to sanctuary cities such as San Francisco.

In addition, Gov. Jerry Brown signed legislation last year imposing limits statewide on cooperation with federal immigration officials, although there are exceptions.

ICE has said it will increase its presence in California, and Sessions wants to cut off funding to jurisdictions that won’t cooperate.

His announcement comes after Oakland Mayor Libby Schaaf warned of an immigration sweep in advance. U.S. Immigration and Customs Enforcement said hundreds of immigrants eluded detention because of her warning. Agents still arrested more than 200 people during a four-day sweep.

White House spokesman Sarah Huckabee Sanders said Schaaf’s tweet was an “outrageous” attempt to circumvent federal authorities and was under review by U.S. Justice officials.

Sessions has blamed sanctuary city policies for crime and gang violence and announced in July that cities and states could only receive certain grants if they cooperate. California is suing to force the administration to release one such grant.

State Attorney General Xavier Becerra is speaking to the same law enforcement organization later Wednesday.

Becerra, a Democrat who is up for election in November, has been sharply critical of Republicans Trump and Sessions, particularly on immigration policies.

He has said federal authorities need to have warrants before collecting information from state employers or entering nonpublic areas.

He and other defenders say sanctuary policies increase public safety by promoting trust between immigrant communities and law enforcement, while allowing police resources to be used to fight other crimes.