Secret Service prepares use of bulletproof glass for outdoor Trump rallies: Sources

The U.S. Secret Service is making arrangements for former President Donald Trump to resume outdoor campaign rallies by surrounding his podium with bulletproof glass, multiple sources told ABC News.

The measure is typically used exclusively for sitting presidents, but the Secret Service is making an exception following the first attempted assassination of a presidential candidate since George Wallace in 1972.

The Secret Service declined to comment on its use of ballistic glass.

Trump campaign spokesperson Steven Cheung said the campaign does not comment on security measures relating to Trump.

The Secret Service recommended that Trump stop holding outdoor rallies last month after a gunman in Butler, Pennsylvania, fired at him from a rooftop 400 feet from the stage, nicking his ear. A man in the crowd was killed in the attack.

Since July 13, Trump has held nearly a dozen campaign events, all of them indoors.

Trump has privately expressed a desire to campaign outdoors and has sought assurances it would be safe, the sources said.

At a rally at an indoor arena in Harrisburg, Pennsylvania, on July 31, Trump complimented the size of the venue then told the crowd, "They'd prefer that we be in an arena. I don't know why. But we're not giving up the outdoor rallies. You know, all those people that we had to turn away today, at an outdoor rally you can have."

Trump's protective detail is preparing for glass panels to surround him on three sides, according to the sources -- though it's not immediately clear when that would start.

"The Secret Service use of UpArmored glass around former President Trump is another step to ensure the campaign is and remains secure," said ABC News contributor Don Mihalek, a retired senior Secret Service agent. "This isn't just a piece of glass but a large, bulky and heavy armored glass that will require extensive logistics capability, normally reserved for large-scale outdoor events."

Typically, the ballistic glass is flown aboard a military cargo plane. In Trump's case the Secret Service is ordering multiple sets to be stored around the country so it can be trucked wherever it's needed, sources said.

Former Secret Service Director Kim Cheatle, in the aftermath of the Butler shooting, beefed up the protective details for Trump, Vice President Kamala Harris, and their running mates. Other protectees, like second gentleman Doug Emhoff, also received an increase in protection, sources said.

Editor's note: This story has been updated to correct the last attempted assassination of a U.S. presidential candidate.