The memorial service for Kirk, whom Trump credits with playing a pivotal role in his 2024 election victory, drew tens of thousands of mourners, including Vice President JD Vance, senior White House officials and young conservatives shaped by the 31-year-old firebrand.

“We’re going to celebrate the life of a great man today,” said Trump, who told reporters he was bracing for a “tough day” as he left the White House for the service in Arizona.

Kirk’s assassination at a September 10 appearance on a Utah college campus has set off a fierce debate about violence, decency, and free speech in an era of deep political division.

The shooting also has stirred fear among some Americans that Trump is trying to harness outrage over the killing as justification to suppress the voices of his critics and political opponents.

The service is at State Farm Stadium, the home of the NFL’s Arizona Cardinals west of Phoenix, where Kirk’s Turning Point organisation is based. Security was tight, with a similar level of federal law enforcement presence as for the Super Bowl or other high-profile event.

Members of the public began lining up outside the stadium before dawn to secure a spot, and the 63,400-seat stadium quickly filled with people dressed in red, white and blue, as organisers suggested.

“I think that this is going to change things, and I think he made such a difference,” said Crystal Herman, who travelled from Branson, Missouri.

“He deserves us to be here.”

Photos of Kirk at work or with his wife, Erika, were on easels throughout the concession areas of the main concourse level. Some people posed for photos next to them.

Comments about Kirk have become a Trump administration target

Trump has blamed the “radical left” for Kirk’s death and threatened to go after liberal organisations and donors or others whom he feels are maligning or celebrating Kirk’s death.

Dozens of people, from journalists to teachers, have lost their jobs as prominent conservative activists and administration officials target comments about Kirk that they deem offensive or celebratory.

The retaliation has in turn ignited a debate over the First Amendment as the Republican administration promises retribution against those who air what are seen as disparaging remarks in the wake of Kirk’s death.

ABC pulled Jimmy Kimmel’s late-night show off the air indefinitely following backlash from affiliated broadcasters and the Trump-appointed head of the Federal Communications Commission over the comedian’s remarks about Kirk.

A 22-year-old Utah man, Tyler Robinson, has been charged with killing Kirk and faces the death penalty if convicted of the most serious charges.

Authorities have not revealed a clear motive in the shooting, but prosecutors say Robinson wrote in a text to his partner following the shooting that he “had enough” of Kirk’s hatred.

Kirk’s legacy of conservative political influence

Turning Point, the group Kirk founded to mobilise young Christian conservatives, became a multimillion-dollar operation under his leadership with enormous reach.

The crowd expected to fill the stadium in Glendale for Kirk’s memorial is a testament to the massive influence he accumulated in conservative America with his ability to mobilise young people.

“I think he spoke on more than just politics,” said Michael Link, 29, who stopped outside the stadium to take in the scene.

“Now that he’s gone, it’s like who’s gonna speak for us now?”

His impact on modern-day conservatism went beyond US shores.

Kirk “was very effective because he was convinced of his views and knew how to argue them,” Italian Premier Giorgia Meloni said at a political rally Sunday in Rome. “But he never stopped smiling, never stopped respecting his interlocutor and anyone who challenged him.”

Kirk was a provocateur who at times made statements that some called racist, misogynistic, anti-immigrant and transphobic. That has drawn backlash from conservatives who view the criticism as cherry-picking a few select moments to insult the legacy they see of an inspirational conservative leader.

Kirk was a MAGA celebrity with a loyal following that turned out to support or argue with him as he travelled the country for the events like the one at Utah Valley University, where he was shot. Kirk grew the organisation, in large part, through the force of his personality and debating chops.

Arizona is the adopted home state of Kirk, who grew up outside Chicago and founded Turning Point there before moving the organisation to Phoenix. Vance has said Kirk’s advocacy was a big reason Trump picked him to serve as vice president.

Scheduled speakers at the service include Trump, Vance, Health and Human Services Secretary Robert F Kennedy Jr, Defence Secretary Pete Hegseth and Director of National Intelligence Tulsi Gabbard. Donald Trump Jr, right-wing commentator Tucker Carlson, and White House aides Stephen Miller and Sergio Gor are also set to speak.

Also speaking will be Kirk’s widow, who has been named Turning Point’s new leader and has pledged that “the movement my husband built will not die.”

Democratic Goernor. Josh Shapiro of Pennsylvania, whose official residence was set ablaze by a suspected arsonist in April while Shapiro was celebrating Passover with his family and friends inside, said in a television interview broadcast Sunday that Americans must now come together to find “our better angels.”

“We’ve got to universally condemn political violence no matter where it is,” Shapiro told NBC’s “Meet the Press.”