President Donald Trump and other prominent American political figures are heading to Arizona to speak at a memorial for Charlie Kirk, the 31-year-old conservative activist who was killed two weeks ago.
The event, organised by Turning Point USA (TPUSA), is on Sunday at State Farm Stadium in Glendale and could be attended by more than 100,000 people.
Heightened security is expected, including "TSA-level screening", according to TPUSA.
Kirk, who co-founded Turning Point USA when he was 18, was shot at a speaking event on a Utah university campus on 10 September, reigniting concerns about political violence in the US.
A polarising figure, differing perspectives about his legacy and possible motives for the shooting have exacerbated deep divisions in the US.
In addition to Trump, those expected to speak at the service include Kirk's widow, Erika, who took over his role as TPUSA CEO; Vice President JD Vance; the president's eldest son, Donald Trump Jr; right-wing political commentator Tucker Carlson; homeland security adviser and White House deputy chief of staff for policy Stephen Miller.
Public shootings in the US are normally met with calls from political leaders for calm, prayer and unity.
But the Trump administration has been seeking to blame and crack down on the "radical left", which in turn has prompted accusations of government overreach and claims Kirk's death is being used as a pretext to intrude on civil liberties.
Doors open at 08:00 local time (16:00 BST), with the official program due to start at 11:00 (19:00 BST). The dress code is "Sunday best - red, white or blue".
The stadium can hold just over 63,000 people, with the TPUSA website stating entry on Sunday will be on a "first come, first served" basis. A nearby 20,000 capacity stadium has been allocated as an overflow area.
It will also be live-streamed on Charlie Kirk's Rumble account, TPUSA said.
At the stadium, organisers said there will be "enhanced security measures" in place with "TSA-level screening".
A senior Department of Homeland Security official told CBS that the memorial service has the same security designation as high-profile events such as the Super Bowl.
The Secret Service told the outlet that a man was "observed exhibiting suspicious behaviour" at the stadium on Friday.
Agents approached the man, who was armed and claimed he was a member of law enforcement, CBS reported.
Officials said the man was booked for impersonating law enforcement and carrying a weapon in a prohibited place, but has been released on bond. TPUSA spokesman Andrew Kolvet later said the man was a private security advisor for a "known" guest who was checking the area ahead of the event.
"We do not believe this person was attempting anything nefarious, however the advance was not done in proper coordination with the TPUSA security team or US Secret Service," he said on social media. "Also important to note that this was before the site had been fully sealed and locked down. Every precaution is being taken to ensure everyone's safety."
Tensions are high following the killing of Kirk.
Much is still unknown about the suspected shooter's motive. Utah's governor said Tyler Robinson, 22, who was charged in the shooting and remains in jail, has a "leftist ideology". And shell casings with anti-fascist slogans were found, according to officials.
But the exact meaning of those and other messages is still unclear.
