Because candidate events often take place in cramped spaces, campaign journalists have long relied on a so-called pool system, in which one reporter attends on behalf of other news organizations. The television pool consists of ABC, CBS, CNN, Fox News and NBC, with the networks taking turns on a preset schedule. Each network selects the individual journalist who is assigned to represent the pool.
A spokesman for the Trump campaign, Steven Cheung, acknowledged that the network pool did not attend the New Hampshire event, but he said the Trump campaign does not “bar reporters based on their reporting.” Mr. Cheung said the campaign holds some events without a network pool, and noted that the pooling system for presidential candidates is less formal than the system in place for covering the president at the White House.
“We work with each other when it makes sense for both sides,” Mr. Cheung said.
NBC News declined to comment. Later on Sunday, Mr. Hillyard was allowed to attend a rally that Mr. Trump was holding at an opera house in Rochester, N.H.
The incident on Sunday echoed several episodes in Mr. Trump’s political career where he barred journalists from attending events or news conferences. In the 2016 campaign, he prohibited reporters from The Washington Post and BuzzFeed News from attending some rallies. As president, his administration revoked a CNN reporter’s press pass and barred certain journalists from some public events.
Mr. Hillyard has irritated Mr. Trump before with questions that the former president deemed impertinent. Last March, during a meeting with journalists aboard his plane, Mr. Trump grabbed Mr. Hillyard’s phone and asked that he be removed. “Get him out of here,” Mr. Trump told aides, according to audio published by Vanity Fair.