The stability of the ideal internal kink mode is calculated, taking intoaccount the kinetic response of thermal ions in the external region and thesingular layer. By extending the collisionless dispersion relation to includethe equilibrium radial electric field it is found that the stability of theinternal kink mode depends sensitively on sheared toroidal plasma rotation.The sheared toroidal plasma rotation can increase the critical pressure forinternal kink mode displacements typically by a factor of two.