Threshold electropion production on nucleons, e+N-->e+N+π, is studied by current-algebra techniques using the hypothesis of partially conserved axial-vector current, which have proved useful in describing low-energy meson-baryon elastic scattering and photopion production on nucleons. The electric and longitudinal multipole moments E0+ and L0+ are calculated at threshold in terms of the form factors of the electromagnetic and weak axial-vector currents. The experimental upper bounds on the slope of the differential cross section as a function of |q|, the momentum in the πN c.m. system, i.e., (1|q|) (d2σdΩdS20L), where S20L is the laboratory energy of the final electron, are sufficiently strong to relate the form factors for various values of -k2, the momentum transfer squared of the electrons. More precisely, in this way one can relate the neutron charge form factor Gen(k2) to normalized axial-vector form factor FA(k2). If one takes FA(k2) to have the dipole form FA(k2)=(1+k2MA2)-2 with MA2=1.42 BeV2, which is given by arguments based on chiral SU(2)×SU(2) and consistent with recent neutrino experiments, then the resulting values of Gen(k2) in the range considered, 0.2<=k2<=0.6 BeV2, are consistent with information about Gen(k2) from electron-deuteron and thermal-neutron-electron scattering.