WASHINGTON — A federal grand jury has added an attempted terrorism charge to the case of Cole Tomas Allen, the man arrested after he opened fire at the White House Correspondents’ Association Dinner in April.

Allen now faces a total of five counts, including a top charge of attempting to assassinate the president of the United States. If convicted, federal prosecutors could potentially seek a federal terrorism sentencing enhancement. Allen previously pleaded not guilty in connection with the April 25 incident. He has not pleaded to the new charge.

Cole Tomas Allen, the man arrested at the White House Correspondents' Association Dinner in April. Dept. of Justice

While there is no federal domestic terrorism statute that broadly outlaws acts of terrorism, Allen has been charged under a local D.C. terrorism law. The same D.C. statute was used against Floyd Fee Corkins, the gunman who was convicted of attacking the Family Research Council in 2012.

The office of the U.S.…