Newt Gingrich said Thursday that special counsel Robert Mueller's Russia probe poses a "deadly" threat to President Trump's agenda.

During a segment of his Fox News television show, host Sean Hannity opined that political noise like the leaks of Trump's phone conversations with the Mexican president and Australian prime minister were "a real threat" to Trump's achieving his legislative and policy goals.

"Well, I think it's very real, and I think it has been all along," Gingrich agreed. "The Mueller threat is probably the most deadly," he added.

Mueller has the power of the law, the ability to indict people, the opportunity to negotiate, and the capacity to bargain with those who testify against other people, Gingrich added.

The former House speaker and presidential candidate has been outspoken about his concern over Mueller's leadership of the Russian investigation, telling the Washington Examiner in June that it was a "presidential hunting expedition with liberal lawyers."

"I regard the Mueller example as 'the Deep State' at its very worst, and it worries me a great deal," Gingrich said Thursday. "It fits the whole case that we've seen about the Justice Department at times being out of control, so that worries me a lot."