WASHINGTON — President Donald Trump named Robert O’Brien as his new national security adviser Wednesday as he seeks to realign his staff and temper internal divisions following the turbulent reign of former national security adviser John Bolton.

The appointment of O’Brien solidifies the status of Secretary of State Mike Pompeo as the most influential foreign policy voice in the administration. Pompeo has known O’Brien for years and backed his ascension to the job after battling with Bolton over an array of policy issues on Afghanistan, Iran and North Korea, U.S. officials said.

O’Brien, who served as the nation’s top hostage negotiator, will now take on a more daunting set of responsibilities as Trump’s fourth national security adviser. He takes over amid escalating tensions with Iran, a high-stakes trade war with China, and concerns about whether he wields enough clout to forge consensus among the U.S. government’s competing egos and agencies.

But officials said they hoped his friendly demeanor and experience as a lawyer could bring more stability and collegiality to an often chaotic policymaking process going into the 2020 election.

“A major concern is cutting back on the drama,” said a senior U.S. official, who like others spoke on the condition of anonymity to speak about internal dynamics.

Trump praised his new pick in Los Angeles on Wednesday, saying O’Brien has “worked with me for quite a while now on hostages and we have a tremendous track record on hostages.”

O’Brien called it a “privilege” to take the adviser role and cited a number of “challenges” he would take on including keeping America safe and rebuilding the military. On the heightened tensions with Iran, he said “we’re looking at those issues now” and he would advise the president privately on how to handle the situation.

Several officials said O’Brien would be less resistant to following the president’s orders than his predecessor, who opposed Trump’s negotiations with North Korea, withdrawal plans in Afghanistan and interest in engaging with Iranian leaders.

O’Brien becomes Trump’s fourth national security adviser since January 2017.

U.S. officials hope O’Brien’s appointment will put an end to the rampant feuding between staffers for Pompeo and Bolton, who at times did not share information with each other out of suspicion that it would be used to undermine their positions ahead of a presidential policy decision.

Inside the Trump administration, O’Brien was viewed as the “safest option” at a time when the national security team wanted as little “drama” as possible going into the 2020 elections, said a senior U.S. official, who requested anonymity.

“He gets along with everybody,” the official said. “He’s the nicest guy on the planet.”

His friendly demeanor contrasts with that of Bolton, who rankled officials at the Pentagon and the State Department with his sharp-elbowed management style and revamp of the policy process that involved fewer meetings for senior officials to air their views.

Officials said a policy process that doesn’t create new competing factions would be welcome, particularly by acting White House chief of staff Mick Mulvaney.

The position of national security adviser does not require Senate confirmation.

O’Brien was a founding partner of a Los Angeles law firm and has also served in U.S. government roles focusing on Afghanistan and the Middle East.

O’Brien has praised Trump for having “unparalleled success” in bringing home hostages, though O’Brien’s July appearance in Sweden to monitor the trial of rapper A$AP Rocky raised eyebrows as critics assailed Trump for what they viewed as an inappropriate intervention in an allied nation’s legal matters.

O’Brien’s prior work with the State Department included serving as co-chairman of its Public-Private Partnership for Justice Reform in Afghanistan from 2007 to 2011. His law firm’s website notes that he served under two secretaries of state, Condoleezza Rice in the Bush administration and Hillary Clinton in the Obama administration.

A former Obama administration official was among those who praised O’Brien’s appointment.

“All I have to say is that @robertcobrien is a really, really good person and that I wish him all the best in what will certainly be a challenging role,” tweeted Andrew Exum, a former deputy assistant secretary of defense for Middle East policy.

The Associated Press contributed.