Two mechanisms of formation of long-lived negative molecular ions in TCNQ at resonant electron capture were considered for the case of the nonzero captured electrons. The first mechanism concerned with the ions lying in energy lower than the first molecular triplet was related to inter-systems crossing process providing formation of the long-lived ions with quartet multiplicity. The second mechanism, which yields high lifetime of the ions lying above the first triplet, was determined as a mixing of ion electronic states with the ground state contribution. The results give more knowledge of the long-lived negative ions formation.