The US Secret Service is under mounting pressure to explain the failings that led to the attempted assassination of Donald Trump.
Republicans are calling for the agency's director, Kimberly Cheatle, to resign, saying she has not provided enough information about how a gunman was able to get so close to the former president.
James Comer, the Republican leader of the House oversight and accountability committee, issued a subpoena on Wednesday compelling Ms Cheatle to give evidence in front of the panel on Monday.
The “lack of transparency and failure to co-operate” with the committee called into question Ms Cheatle's ability to lead the Secret Service and made the subpoena necessary, Mr Comer said.
“The assassination attempt of the former president and current Republican nominee for president represents a total failure of the agency's core mission and demands congressional oversight,” he wrote to Ms Cheatle.
Initial reviews of Saturday's attack, when Thomas Crooks, 20, opened fire from a rooftop with a clear line of sight to Mr Trump, have pointed to a failure of local and federal law enforcement agencies to communicate properly during the rally.
Mr Crooks was able to get within 135 metres of the stage where the Republican candidate was speaking.
That happened despite a threat on Mr Trump’s life from Iran, leading to extra security in the days before the rally.
Conspiracy theories are already swirling online, suggesting the Secret Service knowingly failed to take action against Mr Crooks even though he was seen on the roof minutes before the shooting.
“Now you have the blame game, people pointing fingers,” Mark Esper, former defence secretary under Mr Trump, said at the Aspen Security Forum.
“Is it local or state versus federal? Who did this? Who did that? You have folks on the right who, each side, have conspiracy theories about what happened, what didn't happen.”
House Speaker Mike Johnson, meanwhile, announced he would set up a task force to investigate security failures that occurred during the assassination attempt.
Mr Johnson, a Republican, said he would be calling on Ms Cheatle to resign, telling Fox News: “I think she’s shown what her priorities are.”
He said the task force would be made up of Republicans and Democrats, and its formation would speed up the investigation into the shooting.
“We must have accountability for this. It was inexcusable,” Mr Johnson said. “Obviously, there were security lapses. You don’t have to be a special ops expert to understand that. And we’re going to get down to the bottom of it quickly.”
Ms Cheatle said her agency was working to understand how Saturday’s shooting happened and to make sure there are no such attacks in future. She has said she will not resign.
Matthew Noyes, cyber policy director and strategy director of the Secret Service, said the agency was struggling with low funding.
Also speaking in Aspen, Mr Noyes said it had “long been the case” that the Secret Service had been constrained by limits on its budget.
Adding to those stresses, President Joe Biden has ordered the Secret Service to begin providing protection to third-party candidate Robert F Kennedy Jr. Mr Trump's running mate, JD Vance, also has been assigned a security deal.
Presidential candidates Cornel West and Jill Stein are also seeking Secret Service protection.
“We definitely believe we should have those protections in this political climate,” Dr Stein's representative, Jason Call, told The National.
Trump shooting – in pictures
