The concept of a “deep state” — a shadowy network of agency or military officials who secretly conspire to influence government policy — is more often used to describe countries like Egypt, Turkey and Pakistan, where authoritarian elements band together to undercut democratically elected leaders. But inside the West Wing, Mr. Trump and his inner circle, particularly his chief strategist, Stephen K. Bannon, see the influence of such forces at work within the United States, essentially arguing that their own government is being undermined from within.

It is an extraordinary contention for a sitting president to make.