As the $18 billion sale of Toshiba Corp.'s memory chip unit to a government-approved consortium falters, some bankers and potential investors are pressing the board to seriously consider alternatives,including picking a new buyer, sources said.

Those people say Toshiba's leadership is sticking to plan A: selling the world's second-largest memory chip maker to a Japanese government-backed group that also includes Bain Capital.

But the clock is ticking for Toshiba, which was still recovering from a $1.3 billion accounting scandal in 2015 when it was hit by billions of dollars of cost overruns at its U.S. nuclear unit Westinghouse in December.