Specific Aim #1: To determine if progesterone +TNP is superior to placebo +TNP for prolonged and 7-day point prevalence of smoking abstinence rates at the end of 8 weeks of treatment and at 1 and 3 month follow-up time points. The investigators will also evaluate the safety and tolerability of progesterone treatment, compared to placebo. Our co-primary outcome measures will be 7-day point prevalence of smoking abstinence and breath CO at the end of treatment and 1- and 3-months after the end of the trial. Specific Aim #2: To determine if progesterone + TNP treatment, compared to placebo + TNP, improves response inhibitory function, as assessed by the Stroop, The Go/No Go task, and the Digit Symbol Task. Specific Aim # 3: To determine if progesterone + TNP treatment, compared to placebo + TNP, leads to a greater reduction in cigarette craving and nicotine withdrawal symptoms, as assessed by the Questionnaire on Smoking Urges-Brief (QSU-B) and the Minnesota Nicotine Withdrawal Scale (MNWS), respectively. Specific Aim #4: To evaluate with affective changes, as shown on the Positive and Negative Affect Schedule, mediates the effects of progesterone on smoking abstinence.