(CNN) — As the US Department of Justice gears up to try to indict the man who allegedly plotted to shoot Donald Trump while he was golfing, a federal prosecutor said his team has been focused on one charge in particular: attempting to kill a major presidential candidate. In court Monday, prosecutor Mark Dispoto told a judge that the Justice Department would pursue that charge under Section 351 of Title 18 of the United States Code . The charge carries a potential life sentence in federal prison.

Prosecutors have already charged Ryan Wesley Routh with two firearms offenses, and a federal magistrate judge on Monday ordered him detained pending further court proceedings . He has not yet entered a plea. The attempted assassination charge is “pretty rare,” according to former FBI Deputy Director Andrew McCabe, a CNN senior law enforcement analyst.

But it has been used in other high-profile attempted assassination cases, such as that of a man charged with traveling to Brett Kavanaugh’s Maryland home with a gun, burglary tools and other equipment in an apparent attempt on the Supreme Court justice’s life. To prove their case, prosecutors would have to convince a jury that Routh took affirmative steps to carry out a plot to kill the former president. They would likely point to evidence already revealed in court, including a letter Routh allegedly wrote to “The World” that read, “This was an assassination attempt on Donald Trump but I failed you.

I tried my best and ga.