Running for the consulship for a second time after having lost at the first attempt, Catiline was an advocate for the poor, calling for the cancellation of debts and land redistribution. There was apparently substantial evidence that he had bribed numerous senators to vote for him and engaged in other unethical conduct related to the election (such behaviour was, however, hardly unknown in the late Republic). Cicero, in indignation, issued a law prohibiting such machinations, and it seemed obvious to all that the law was directed at Catiline. Catiline, therefore, so Cicero claimed, conspired to murder Cicero and other key senators on the day of the election, in what became known as the Second Catilinarian conspiracy. Cicero announced that he had discovered the plan, and postponed the election to give the Senate time to discuss this supposed coup d'état.
The day after that originally scheduled for the election, Cicero addressed the Senate on the matter, and Catiline's reaction was immediate and violent. In response to Catiline's behavior, the Senate issued a senatus consultum ultimum, a declaration of martial law. Ordinary law was suspended, and Cicero, as consul, was invested with absolute power.
When the election was finally held, Catiline lost again. Anticipating the bad news, the conspirators had already begun to assemble an army, made up mostly of Lucius Cornelius Sulla's veteran soldiers. The nucleus of conspirators was also joined by some senators. The plan was to initiate an insurrection in all of Italy, put Rome to the torch and, according to Cicero, kill as many senators as they could.
Through his own investigations, he was aware of the conspiracy. On November 8, Cicero called for a meeting of the Senate in the Temple of Jupiter Stator, near the forum, which was used for that purpose only when great danger was imminent. Catiline attended as well. It was then that Cicero delivered one of his most famous orations.