A decision isn't expected to be imminent, one source said, but debate within the administration has shifted recently to more deeply exploring how and when the act might be invoked.

WASHINGTON — White House officials have held increasingly serious discussions in recent days about President Donald Trump’s invoking the Insurrection Act, a rarely used 19th century law that gives the president the power to deploy active-duty troops inside the United States for law enforcement purposes, five people with knowledge of the talks told NBC News.