We consider the unwinding of a tethered, flexible, and weakly charged polye
lectrolyte in a salt-free poor solvent under an externally imposed strain.
Using scaling arguments, we predict that the restoring force of a stretched
polyelectrolyte shows a sawtooth pattern as a function of the externally i
mposed end-to-end distance. This nonmonotonic behavior arises from a cascad
e of conformational transitions between necklace-like structures with diffe
rent number of beads. The transitions result from the interplay between the
unscreened Coulomb repulsion of charged monomers and the short-range attra
ction of the backbone.