U.S. President Trump is holding a 2020 campaign rally on Saturday night in Tulsa, Oklahoma, the first since the COVID-19 pandemic shutdown public gatherings. 

Supporters have been in line for days outside the arena where the rally will be held. At least 100,000 people are expected in downtown Tulsa. 

President Trump issued a warning on Twitter to counter protesters at the rally, saying:

Trump's campaign rally was originally scheduled for June 19th, known as Juneteenth, a day that marks freedom for all enslaved African Americans in the U.S. But after facing criticism over the rally date, it was moved to Saturday.

Trump is also facing criticism for holding the rally at all, during a pandemic and in Tulsa, home to one of the deadliest race massacres in U.S. history.

Supporters who will attend the rally had to register online for the event and waive their rights to hold the campaign liable if they catch COVID-19. 

By registering to attend, supporters "are acknowledging that an inherent risk of exposure to COVID-19 exists in any public place where people are present," the waiver states, adding that attendees and guests "voluntarily assume all risks related to exposure to COVID-19" and agree to not hold the Trump campaign, the venue or other organizers liable.