Fine Gael has published a Bill, which proposes reducing the number of Ministers of State to 12.
The resignation of all 20 existing junior ministers will to come into effect at midnight tonight.
The Taoiseach has said he will reappoint 15 Ministers of State tomorrow.
However, Fine Gael's Alan Shatter says the reduction of five does not go far enough.
He said that in the absence of legislation to reduce the maximum number of junior ministers, the positions could be filled again in the future.