Christian Porter is expected to be stripped of his attorney-general portfolio while he sues the ABC over its reporting of rape allegations, which he denies.
Defence Minister Linda Reynolds is also set to shift positions in the reshuffle.
The prime minister refused to confirm the looming reshuffle, which is expected as early as Friday.
"All I can say is that when I make decisions on these matters I will communicate them and my reasons for them," he told ABC radio on Thursday.
Mr Morrison has received advice from the solicitor-general about direct conflicts of interest that might arise from Mr Porter's legal action.
He has also sought advice from his department in relation to the attorney-general and ministerial standards, as they relate to perceived conflicts of interest.
"I'm working through those issues with the attorney at the moment," Mr Morrison said.
"He's not returning to work for another week or so yet, and that will be done in time for his return."
The prime minister insists his own position is "absolutely" safe.
"I've been very grateful for the tremendous support I've had from all of my colleagues," he said.
"From my cabinet, my ministers, all the way through to my party room. I have just been overwhelmed by the amount of support that I have received from my colleagues this week. Our party has never been more united."
Mr Porter has been on stress leave since publicly naming himself as the minister against whom a historical rape allegation had been made.
He strongly denies the allegation and has launched defamation action against the ABC.
Acting attorney-general Michaelia Cash appears the most likely to replace him.
Senator Reynolds went on leave a month ago to receive treatment for a pre-existing heart condition.
At the time, she was facing intense pressure over her handling of rape allegations raised by former staffer Brittany Higgins.
Senator Reynolds could be replaced in defence by Home Affairs Minister Peter Dutton.
She is due to return on April 2 and Mr Porter on March 31.