Treasury Secretary Steven Mnuchin said Thursday that the Treasury Department could scrap plans finalized under President Barack Obama to replace President Andrew Jackson on the front of the $20 bill with Harriet Tubman.

Mnuchin told CNBC that he's not focused on the planned currency changes, and wouldn't commit to following through on them.

He said the primary reason the Treasury changes the design of bills is to prevent counterfeiting, something Obama administration officials also emphasized when announcing the changes in April 2016.

"It's not something that I'm focused on at the moment" Mnuchin said. "The issues of why we change it will be primarily related to what we need to do for security purposes."

The Treasury Department announced changes to the $20, $10 and $5 bills last year. The department initially planned to place Jackson's image with an image of the White House on the back of the $20 bill.

New designs for the back of the $10 bill featured leaders of the suffrage movement, while the back of the $5 bill would feature depictions of historic civil rights events at the Lincoln Memorial.