washington u.s. senate overwhelmingly back waiver thursday allow jam mattis serve president-elect donald trump secretary defense despite retire marine general 2013. senate vote 81 17 one-time waiver provision law civilian control u.s. military require seven-year wait active-duty military lead department defense waiver must still approve house representatives arm service committee full house sign law president allow mattis serve confirm lead pentagon u.s. senate back waiver allow mattis lead pentagon