Khizr Khan, the Gold Star father who came under attack from Donald Trump during the 2016 presidential campaign after offering to lend the Republican a copy of the Constitution, will appear at a rally on Tuesday for Jason Crow, a Democrat challenging U.S. Rep. Mike Coffman in Colorado’s 6th Congressional District, Crow’s campaign said Friday.

Also appearing at the rally will be the president of campaign finance reform group End Citizens United, Tiffany Muller, and state Reps. Dafna Michaelson-Jenet, D-Commerce City, and Jovan Melton, D-Aurora.

In December, Khan endorsed Crow, calling the Aurora attorney and decorated Army Ranger combat veteran “someone who goes where the fight is.”

Khan, whose son Army Capt. Humayun Khan was killed by a suicide bomber in Iraq in 2004, criticized Trump’s proposal to ban Muslims from entering the United States in a speech at the 2016 Democratic National Convention.

Noting that he emigrated to the United States with his wife and son from the United Arab Emirates, Khan waved a pocket copy of the Constitution during the speech and addressed Trump: “Let me ask you – have you even read the United States Constitution? I will gladly lend you my copy. In this document, look for the words ‘liberty’ and ‘equal protection of law.'”

After Trump attacked the Khans, the feud dominated the news for days and drew rebukes from national GOP leaders and prominent Colorado Republicans, including Coffman, an Army and Marine Corps combat veteran.

“Having served in Iraq, I’m deeply offended when Donald Trump fails to honor the sacrifices of all of our brave soldiers who were lost in that war,” Coffman said in an interview with The New York Times.

End Citizens United has also endorsed Crow, one of four Democrats running in a primary in the battleground suburban district.

The rally is scheduled for 7-8 p.m. Tuesday at the Plumbers Local 3 union hall, 17100 E. 32nd Place, in Aurora. Doors open at 6:30 p.m.

The other Democrats running for the seat are clean energy expert and author Levi Tillemann, Aurora attorney and former school board candidate David Aarestad and political newcomer Erik Stanger. Coffman is facing a primary challenge from Highlands Ranch activist Roger Edwards.

Precinct caucuses are March 6, and the primary election is June 26.