The Obama administration is winning praise from conservative Republicans for initiating a change in federal policy that could encourage so-called sanctuary cities to abandon their stance against cooperating with deportation requests.

The move could be politically awkward for Democratic presidential candidates Hillary Clinton and Bernie Sanders, both of whom are aggressively courting immigrant communities while also expressing solidarity with President Barack Obama.

Under the new policy, the federal Bureau of Prisons will put prisoners finishing their sentences into immigration custody by default when immigration authorities seek deportation, even if local or state officials want the immigrant for prosecution or to finish a state or local sentence. Immigration officials may sometimes defer to state or local authorities, but will take into account a locality's cooperation with federal deportation requests in deciding whether to hand over a prisoner.

The new policy places the extra restraints on any city, county or state that chooses to adopt a so-called "sanctuary" policy, particularly a categorical one that bars all cooperation with immigration authorities.