When he was the U.S. attorney for New Jersey, Christie prosecuted Kushner's father, real estate mogul Charles Kushner, who was sentenced to prison in 2005 on 18 counts of tax evasion, witness tampering and making illegal campaign contributions.
Christie was one of the biggest supporters of Donald Trump's presidential campaign last year and, according to two top Republican officials, was vetted as a possible vice presidential pick. Trump ultimately chose Mike Pence as his running mate and asked Christie to head his transition team. Just days after Trump's election victory over Democratic candidate Hillary Clinton, Trump asked Pence to take over transition team efforts from Christie.
The staff shakeup coincided with unconfirmed reports that Jared Kushner, who is married to Ivanka Trump, was at the center of infighting among transition team members. But in a rare interview with Forbes last year, Kushner denied that he was behind Christie's ouster.
"Six months ago, Gov. Christie and I decided this election was much bigger than any differences we may have had in the past, and we worked very well together," Kushner told Forbes last November. "The media has speculated on a lot of different things, and since I don't talk to the press, they go as they go, but I was not behind pushing out him or his people."
Now Christie is set to lead a new White House commission tasked with tackling opioid addiction nationwide. The commission will fall under the White House Office of American Innovation, which Trump unveiled Monday. The president appointed Kushner to lead the office.
"The Office of American Innovation will bring a creative and strategic approach to many critical issues and intractable problems that affect Americans' quality of life," Kushner said in a statement issued by the White House on Monday. "We have an opportunity to identify and implement solutions by combining internal resources with the private sector's innovation and creativity, enabling the federal government to better serve Americans."
According to the Centers for Disease Control and Prevention, 91 Americans die every day from overdosing on opioids, including heroin and prescription opioids. Deaths in the United States from prescription opioids such as oxycodone, hydrocodone and methadone have more than quadrupled since 1999.
"They do need the help, and this White House is going to step up to help them," Christie told "GMA."
In addition to addressing the epidemic of opioid and other drug use, the White House Office of American Innovation will create task forces to focus on other initiatives, including reforming care for veterans.
"Listen, that stuff is ancient history. It's over 12 years ago. And Jared and I have worked incredibly well on this issue and, by the way, on a whole bunch of other issues during the campaign," Christie added. "We are working hard because we know our job is to try to make sure that this White House is as successful as it can be for the people of this country who elected Donald Trump to bring change to our country and bring change to this town. And anything I can do to help, I will, and Jared and I get along just great."