Former UN peacekeeper Andrew Mitchell will become the new chief whip in the coalition's first major reshuffle, Downing Street has announced.
Mr Mitchell leaves his post as Secretary of State for International Development to replace Patrick McLoughlin in the key enforcer role for a Tory party that has become increasingly rebellious.
Prime Minister David Cameron made the appointment first to allow Mr Mitchell to be involved in the discussions about the rest of the shake-up.
The reshuffle is expected to see ministerial jobs given to a raft of new faces from the 2010 intake as Mr Cameron considers who he wants around him in the run-up to the next general election.
Former Liberal Democrat Treasury minister David Laws is predicted to make a return to the front benches, while key figures such as Chancellor George Osborne and Foreign Secretary William Hague are widely expected to remain in place.
Mr Cameron said: "Andrew has done a superb job as Britain's Development Secretary. He has made British development policy transparent, focused and highly effective. His energy and passionate commitment have placed Britain at the forefront of international efforts to improve the lives of millions of the world's poorest people. He has made a real difference.
"As Chief Whip, Andrew will ensure strong support for our radical legislative programme, by working hard to win the argument in the Commons as well as playing a big role in the No 10 team. He will be invaluable as the Government embarks on the next, vital phase of its mission to restore our economy to growth and reform our public services."
The new chief whip faces the tricky task of corralling the Conservative party's backbenchers, many of whom have found coalition politics increasingly unpalatable. Traditionally new intake MPs toe the party line, fearful of upsetting the leadership and ruining their future chances of promotion but the sheer scale of the number of freshly elected Tories in the last election emboldened many to speak out on contentious areas of policy and rebel in key votes.
Mr Mitchell said: "I leave the Department for International Development with great sadness but I very much look forward to the task ahead."
Although both sides of the coalition have lost key cabinet ministers since the Government was formed in May 2010, this is the first major planned overhaul of the administration. Mr Cameron has always made clear his dislike of past traditions for regular reshuffles but will hope the changes will reinvigorate his government.