The White House blocked Politico from Air Force One on Monday, preventing the outlet from carrying out its assigned responsibilities in the traveling press pool as President Donald Trump headed to Nebraska. A Politico spokesperson confirmed the exclusion to MS NOW.

Politico had been designated as the print outlet for the out of town travel pool during Trump’s visit to Grand Island. Trump was scheduled to appear Monday at a rally with incumbent Republican Sen. Pete Ricketts.

The pool arrangement is a longstanding agreement between the White House and news organizations. A small group of journalists travels with and observes the president, then shares its reporting with the broader White House press corps.

That system gives smaller outlets access to a daily record of the presidency without requiring them to cover the associated travel costs. Politico’s exclusion left the organization unable to perform the pool duties it had been assigned for the Nebraska trip.

The White House Correspondents’ Association determines the daily rotation for the primary print pool. The White House generally distributes guidance each night detailing the pool coverage planned for the following day.

Guidance sent Sunday evening listed the journalists assigned to Monday’s coverage within Washington. It did not, however, identify the outlet responsible for the out of town pool, even though Politico had been assigned that role.

A White House official characterized traveling with the president aboard Air Force One as “a privilege not a right.” The official also pledged that Trump “will continue to grant an unprecedented level of access to the press.”

The statement came as the federal government’s feud with media organizations continues to deepen. The decision to exclude Politico from the presidential plane was first reported by CNN.

Trump has sought to ban outlets including MS NOW from the White House. MS NOW, CNN and Politico sued the White House over that ban, and a judge temporarily blocked it last month.

Even after the temporary order, some journalists from those organizations have been denied access to the White House or Air Force One. The Trump administration maintained in a new filing on Friday that it has the authority to ban the journalists.

The current legal dispute focuses on access to the White House itself as it existed before Trump’s ban took effect Sept. 18. The lawsuit does not directly resolve whether the administration can restrict participation in the presidential press pool.

Still, pool access has surfaced in related court filings because news organizations must hold White House credentials to participate. The dispute is also likely to arise during a hearing scheduled for Thursday.

The administration’s latest decision to block Politico from Air Force One may rest on stronger legal footing than its broader White House ban. That distinction stems from a ruling last year involving The Associated Press.

In that case, the U.S. Court of Appeals for the D.C. Circuit held that the Trump administration could restrict certain news organizations from spaces including the Oval Office and Air Force One. The court concluded that those spaces are not official forums.

That case remains ongoing, leaving the broader legal fight unresolved. Meanwhile, Politico’s blocked flight marks another escalation in the confrontation over which journalists may directly observe and report on the president.