California Democrats are considering creating a state-wide sanctuary rule that will prohibit police officers from working with federal immigration authorities in opposition to President Donald Trump's migration policy.

A number of cities, including San Francisco and Los Angeles, already operate such a policy – but it does not cover the entire state. It means they do not cooperate with US Immigration and Customs enforcement—for example, by not notifying immigration officials if an illegal immigrant is about to be released from custody. Around 300 US jurisdictions are believed to currently have sanctuary status.

Mr Trump issued an executive order threatening to strip federal funding from sanctuary cities if they "harbour illegal immigrants" and San Francisco is already suing him on the basis the order contradicts states' rights provisions under US law.

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The new plan, drafted by California Senate president Pro Tem Kevin de Leon, was due for its first airing on Tuesday.

The city of San Francisco said the executive order could result in the loss of more than $1bn (£794m) in funding.

Mr Trump's crackdown was foreshadowed not long after his victory in November's election.

Chief of staff Reince Priebus said cities that "ignore federal law" should not expect "federal government to help them in any way". Ending cities' sanctuary rules was a Trump campaign promise.