Five months after insisting he wanted out of the spotlight, Khizr Khan is still waging a public battle against Donald Trump. Khan, the Muslim Gold Star parent who spoke out against Trump at the Democratic National Convention last July, wrote a letter Monday urging the Senate to oppose Alabama Sen. Jeff Sessions, Trump’s nominee for attorney general.

As he did in his speech at the DNC, Khan used the death of his son, U.S. Army Captain Humayun Khan, who died in Iraq in 2004, as political ammunition.

wrote in his letter.

“My son, US Army Captain Humayun Khan, was a living rebuke to such bigotry. He gave his life in service to this country, earning a Purple Heart and the Bronze Star for his heroism. He, like the people of every gender, ethnicity, and religion whose bodies rest in Arlington National Cemetery, which include FIVE Muslim Soldiers, swore an oath to protect the Constitution.”

After Khan criticized Trump at the DNC and questioned whether Trump had ever read the Constitution, Trump fired back, questioning why Khan’s wife was silent during the speech.

As the public feud dragged on, Khan claimed in a TV interview that he and his wife were private citizens who didn’t want to be in the spotlight.

“We are private citizens. We are private people. We want to be out of this controversy,” Khan said in an appearance on CNN’s “New Day.”

“My good wife, Ghazala, had been insisting that I not respond. I let — I take a more dignified path than responding to undignified attacks and comments. Therefore, we jointly decide that there is no need to escalate this. We have made the point.”

He later appeared in a campaign ad for Hillary Clinton in October and spoke at a Clinton rally just days before the election.

Khan’s letter Monday received coverage from CNN, The Huffington Post, Politico and Time magazine, among others.