Republican Senator John Ensign publicly admitted Tuesday to having an affair with a campaign staffer, and sources say blackmail was involved in his decision to own up to the indiscretion. In a press conference in Las Vegas, the prominent Nevada Senator expressed deep regret and apologized for his actions. Politico reports that after Ensign reconciled with his wife, he gave the aide he had an affair with a severance package. Later, the Senator met with the aide's husband, who asked for a substantial amount of money, which is when Ensign decided to make the affair public. Ensign’s current aide (who asked to remain anonymous) said the affair lasted from December 2007 to August 2008, and that the woman was married to another of Ensign’s employees. The Senator is considered a rising star of the Republican party, and there were rumors he was planning a presidential bid for 2012.