We describe scalar-pseudoscalar partner degeneration at the QCD chiral transition in terms of the dominant low-energy physical states for the light quark sector. First, we obtain within model-independent one-loop chiral perturbation theory that the QCD pseudoscalar susceptibility is proportional to the quark condensate at low $T$. Next, we show that this chiral-restoring behavior for ${\ensuremath{\chi}}_{P}$ is compatible with recent lattice results for screening masses and gives rise to degeneration between the scalar and pseudoscalar susceptibilities $({\ensuremath{\chi}}_{S},{\ensuremath{\chi}}_{P})$ around the transition point, consistently with an $O(4)$-like current restoration pattern. This scenario is clearly confirmed by lattice data when we compare ${\ensuremath{\chi}}_{S}(T)$ with the quark condensate, expected to scale as ${\ensuremath{\chi}}_{P}(T)$. Finally, we show that saturating ${\ensuremath{\chi}}_{S}$ with the $\ensuremath{\sigma}/{f}_{0}(500)$ broad resonance observed in pion scattering and including its finite temperature dependence, allows us to describe the peak structure of ${\ensuremath{\chi}}_{S}(T)$ in lattice data and the associated critical temperature. This is carried out within a unitarized chiral perturbation theory scheme which generates the resonant state dynamically and is also consistent with partner degeneration.