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WASHINGTON — In recent conversations with confidants, President Donald Trump has added FBI Director Christopher Wray to his list of key members of his administration whom he complains about, three people familiar with the discussions tell NBC News.

Trump has criticized Wray as another figure in the Justice Department who is not protecting his interests — and is possibly out to undermine his presidency, these people said.

Trump is "in the worst mood of his presidency and calling friends and allies to vent about his selection of (Attorney General Jeff) Sessions and Wray," said one person familiar with the president’s thinking. This person said the president was particularly focused on both men over the Labor Day weekend.

Trump has frequently tweeted about the Russia probe and more than once has criticized the Justice Department, the FBI and Sessions by name. But until now, the president has been cautious about publicly criticizing the person he appointed after firing former FBI Director James Comey.

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Now he’s increasingly grouping Wray with Sessions, Deputy Attorney General Rod Rosenstein and the special counsel’s Russia investigation, all subjects of relentless criticism from the president.

Trump nominated Wray for the FBI post last summer, weeks after the appointment of special counsel Robert Mueller and months after Sessions recused himself from the Russia investigation.

Since then, Wray has largely avoided the president’s public ire. While Trump has criticized the FBI generally, saying the bureau is biased against him, he has not gone after Wray personally.

That has changed, the people familiar with the president’s thinking said, as Trump’s frustration with his Justice Department has escalated. He’s pointed to issues such as the resistance by the FBI to turn over documents to congressional Republicans. The FBI declined to comment for this story. NBC News has reached out to the White House for comment.

Wray has defended the FBI against Trump’s attacks. In December, after Trump said the FBI’s reputation was in "tatters," Wray pushed back publicly.

"The FBI that I see is tens of thousands of agents and analysts and staff working their tails off to keep Americans safe from the next terrorist attack, gang violence, child predators, spies from Russia, China, North Korea and Iran," he said during a congressional hearing.

Trump has at times been wound up by Tom Fitton, the president of the conservative advocacy group Judicial Watch, and a regular commentator on Fox News, who has been sharply critical of Wray and what he describes as corruption at the FBI.

Wray has reportedly threatened to resign at least once over potential pressure from the president to fire his then-deputy Andrew McCabe. Asked in July by NBC’s Lester Holt whether he’d ever reached a point where a line had been crossed and he threatened to resign, Wray did not deny he had.

"I'm a low-key, understated guy, but that should not be mistaken for what my spine is made out of. I'll just leave it at that," Wray said.