  After application of an analytical transformation, a new exact representation
for the nuclear isospin-symmetry breaking correction $\delta_C$ to superallowed
beta decay is obtained. The correction is shown to be essentially the
reciprocal of the square of an energy parameter $\Omega_M$ which characterizes
the charge-exchange monopole strength distribution. The proportionality
coefficient in this relation is determined by basic properties of the ground
state of the even-even parent nucleus, and should be reliably calculable in any
realistic nuclear model. Therefore, the single parameter $\Omega_M$ contains
all the information about the properties of excited $0^+$ states needed to
describe $\delta_C$. This parameter can possibly be determined experimentally
by charge-exchange reactions. Basic quantities of interest are calculated
within the isospin-consistent continuum random phase approximation, and the
values of $\delta_C$ are compared with the corresponding results from other
approaches.
