The Trump White House has removed CNN from its Monday assignment as the television pool representative for the entire White House press corps.

The change breaks with decades of precedent and deepens the dispute that began Friday when President Donald Trump said he was “banning” CNN, MS NOW and Politico from the White House.

Reporters for all three publications were turned away from the White House complex on Saturday morning. The publications are now preparing a First Amendment lawsuit to challenge the restriction.

The White House typically sends out a “daily guidance and press schedule” email with the rotation for the next day, identifying TV, print, radio and new media outlets that will be part of the pool.

As part of the regular pool rotation, CNN was scheduled to act as the TV pool on Monday, and was assigned as the TV pool network that would accompany Trump to New York for the annual United Nations General Assembly this week.

But a Sunday night email from the White House did not list any television network as the primary TV pool for Monday.

Hearst, which owns local TV stations across the country, was listed as the “secondary” TV crew in DC, and Real America’s Voice, a small pro-Trump network, was listed as the “secondary” crew for the New York trip.

The “secondary” TV assignment usually joins in the pool and questions the president during Q&As, but does not perform the duties of the primary TV pool.

Under a long-standing arrangement, the five big networks — ABC, CBS, CNN, NBC and Fox News — share TV pool responsibility, filming the president and providing live footage to one another and to the wider press corps.

Local TV stations, newspaper websites and media outlets worldwide use the TV pool coverage, acting as the primary way the president is seen by the public.

It is not immediately clear how the other four major TV networks will respond to CNN’s exclusion. Some media critics have urged the networks to publicly show solidarity.

As an immediate matter, CNN’s removal creates uncertainty about pool coverage for Trump’s trip to New York.

For pool coverage, each network takes a daily turn supplying a camera operator, an audio technician and a producer or reporter. While the technical crew records the president, the producer or reporter coordinates the live feed by phone, taking notes and asking questions.

That system, which has remained mostly unchanged for decades, lets a single TV crew provide coverage for many news organizations when space or access is limited, making CNN’s exclusion consequential beyond its own newsroom.

Presidential coverage is also costly, with multi-day trips costing tens of thousands of dollars for the news outlets involved.

“CNN’s mission to report on the U.S. government will continue regardless of any attempts to restrict physical access to the White House and other government buildings, or any other attempts to impede our journalism,” the network said in a statement on Saturday.

“We have a right under the U.S. Constitution to do our reporting without hindrance or interference from the government and this ban is an illegal assault on this fundamental right,” the network added.