Trump remains popular with about 80 percent of the GOP base and that should be enough to cut off any serious attempt to run against him in the Republican primaries, Christie said Monday on Bloomberg Television.

“That doesn’t leave you a whole lot of room to challenge him,” Christie said. “If those numbers change then there will obviously be people who look at it. Because there are always ambitious people who want to run for president of the United States.”

But he added, “I don’t see a landing strip for them.”

Fifty-five percent of the public disapproves of the job Trump is doing, according to the average of recent polls compiled by RealClear Politics.

Christie also repeated his assertion that Trump’s White House is a “Game of Thrones Operation” that hasn’t served the president well. He said that’s partly the result of decisions by Trump’s advisers to discard the transition effort he’d led.

‘Bad Choices’

“I’m a subscriber to the garbage-in garbage-out theory of management, and if you’re giving him bad choices he can’t possibly make good ones and if he does it’s just lucky,” Christie said. “A lot of the folks who they put in front of him, didn’t belong being in front of him.”

In the Democratic nomination race, Christie said his state’s junior Democratic senator, Cory Booker, will be a “credible” candidate in 2020.

As New Jersey governor, Christie worked with Booker while he was the mayor of Newark. In 2010, Booker partnered with Christie when Facebook Inc. co-founder Mark Zuckerberg announced he’d donate $100 million to Newark’s struggling, state-run schools. The two again teamed up to modify teacher tenure rules and expand charter schools in the city.

“We have a friendship,” Christie, who is promoting his memoir “Let Me Finish,” said of Booker. “He has a legitimate chance, but I won’t be doing any endorsement and it won’t be hard for me me to say I’m with the president.”

Booker is among more than a dozen Democrats who’ve announced they will vie for the chance to challenge Trump or are considering bids. The field so far includes Senators Kamala Harris of California, Elizabeth Warren of Massachusetts and Kirsten Gillibrand, Hawaii Representative Tulsi Gabbard, former San Antonio Mayor and Obama administration cabinet official Julian Castro and South Bend, Indiana, Mayor Pete Buttigieg. DM