Currently, the size of the cabinet can not exceed a quarter of the number of MPs.
However, Mr Salwai wants this to be increased to a third, which means cabinet can be increased from 13 to 17 ministers.
Vanuatu's parliament is to have a special sitting tomorrow to debate the required constitutional amendment.
Tess Newton Cain of TNC Pacific Consulting said Mr Salwai's ostensible reason for the expansion is that some ministers have been assigned too many portfolios, and they need to be divided up to be more manageable.