John Kelly, a no-nonsense retired Marine Corps general, was sworn in Monday as the White House chief of staff, tasked with trying to bring order to Donald Trump's presidency six months into his tenure.
"He's going to do a really great job," Trump said as he welcomed Kelly, while touting the country's economic performance.
"Stock market’s the highest it’s ever been, unemployment lowest in 17 years, companies are doing tremendously well, business spirit is the highest it’s ever been according to polls," Trump said. "We’re doing very well, we have a tremendous base, we have a tremendous group of support, the country is optimistic, and I think the general will just add to it."
WATCH: Trump talks to media bout Kelly after swearing-in ceremony
Trump ousted Reince Priebus, an establishment Republican figure, from the posting on Friday, instead tapping the 67-year-old Kelly. Trump has only known him for a matter of months but has come to admire Kelly for his tough stance on fighting illegal immigration while serving as his Homeland Security chief. Trump called Kelly "a star" of his administration.
Kelly, while still holding a high-ranking military posting, became the highest-ranking U.S. officer to lose a child fighting overseas. His son Robert, a Marine Corps officer, stepped on a landmine in Afghanistan in 2010 and was killed. On Memorial Day in late May, Kelly showed Trump his son's gravesite at Arlington National Cemetery just outside Washington.
The early months of Trump's four-year term have been marked by infighting among White House aides, several of whom he has already dismissed for a variety of reasons.
By contrast, Kelly could bring a new discipline to the day-to-day West Wing operations of the White House, but several key aides have become accustomed to popping in unannounced to Trump's Oval Office for conversations with the chief executive. News accounts say that Kelly has griped privately for months about the White House's chaotic life.
WATCH: Trump on his hopes for Kelly at cabinet meeting
Analysts already are questioning whether the unpredictable Trump is willing to impose new order on his own conduct, often marked by acerbic and surprising Twitter comments from early morning to late at night, with political barbs aimed at Democrats and Republicans alike.
In one early morning tweet ahead of Kelly's swearing-in, Trump contended there is "No WH chaos!"
But Trump has yet to score a major legislative victory for his populist agenda, with the latest setback last week when the Senate rejected several plans to overhaul the country's health care law, commonly known as Obamacare, that was championed by former President Barack Obama. Trump has called on the Senate to continue its efforts to repeal and replace the law, but all Democratic senators and a handful of Republicans have resisted.
Mired in investigations
Meanwhile, Trump's presidency remains mired in months of investigations into Russia's meddling in the 2016 election aimed at helping Trump win.
Trump has called the probes a "witch hunt," dismissing them as attempts by Democrats to explain his upset win over his Democratic challenger, former U.S. Secretary of State Hillary Clinton. Numerous congressional investigations are underway, as is a criminal probe by Special Counsel Robert Mueller, a former director of the Federal Bureau of Investigation.
Mueller is looking into whether Trump campaign aides colluded with Russian interests in the election to undermine Clinton's candidacy and whether Trump obstructed justice by firing James Comey, another former FBI director who was heading the agency's Russia investigation before Mueller took over.