David Cameron confirmed Tuesday that International Development Secretary Andrew Mitchell would become chief whip, to build support for the "mission to restore our economy to growth."
Sayeeda Warsi, the first female Muslim to serve in a British Cabinet, posted a message to Twitter confirming she would leave her post as Conservative Party co-chairman.
Welsh Secretary Cheryl Gillan also announced she had lost her role.
Cameron is not expected to switch key ministers, retaining Treasury chief George Osborne to lead economic policy.
Osborne, responsible for sharp public spending cuts, faced a chorus of boos Monday at a Paralympic Games medal ceremony.