Simmering tension between Donald J. Trump and the television networks that cover him entered an extraordinary new phase on Friday, as a consortium of news executives refused to participate in a media session with Mr. Trump after his aides barred a producer from attending.

In a quickly arranged conference call, the network bureau chiefs who oversee the pooled television coverage of Mr. Trump, the Republican presidential nominee, agreed to forgo coverage of a tour of his new luxury hotel in Washington, declining the access because the Trump campaign would allow in only a cameraman, and not a reporter or producer who could ask questions of the candidate.

It was an unusual show of solidarity by a television news industry that has profited handsomely from Mr. Trump’s success, even as its journalists have been routinely taunted and confounded by a candidate with a penchant for lies and bullying.

But Friday also brought perhaps the news media’s most ignominious moment yet.

Mr. Trump extracted nearly an hour of uninterrupted airtime from the cable news networks to promote his hotel, after promising a major revelation and a news conference about his views on President Obama’s birthplace. In a break from typical practice, the networks televised the speeches of supporters who were introducing Mr. Trump, a privilege rarely granted during appearances by the Democratic nominee, Hillary Clinton.