The U.S. Secret Service has dispatched some members of President Joe Biden’s protective detail to assist former president Donald Trump and Vice President Kamala Harris in advance planning for campaign rallies and other events, officials said Friday.

Officials said the agents from the Presidential Protective Division are working to coordinate and enhance security for the candidates in the run-up to the November election.

For Trump, the Republican nominee, officials said the increased assistance followed the July 13 assassination attempt against him at a campaign rally in Butler, Pa.

Harris, the Democratic nominee, has heightened security as vice president but is also benefiting from additional expertise from Biden’s security team, officials said.

As president, Biden receives the highest level of Secret Service protection in the United States on a daily basis, officials said. The agents assisting the candidates are not among those assigned to shield Biden. But Biden is traveling less since he dropped out of the presidential race, freeing up some security personnel to assist the candidates as they campaign.

The Presidential Protective Division includes several hundred highly trained special agents, as well as technical experts and other personnel, said agency spokeswoman Alexi Worley.

“On a case-by-case basis for complex and large-scale events, experienced Presidential Protective Division personnel may assist in advance planning for former President Donald Trump and other high-level protectees,” Worley said in a statement, adding that the others included Harris. “This support is separate from Presidential Protective Division operational demands.”

Harris announced her candidacy for president after Biden withdrew from the race and endorsed her last month.

Secret Service officials said adjusting resources is common when needs arise, such as when world leaders visit the United States or for major gatherings such as the U.N. General Assembly in New York.

The agency, which protects more than 30 people, is also intensely busy in an election year. In Trump’s case, the agency’s top officials testified before Congress that they immediately expanded his security after the shooting at the rally.

The Secret Service came under intense scrutiny after the shooting — considered the worst attack on a U.S. leader under the agency’s protection in four decades. Multiple investigations are examining why law enforcement officers failed to intercept a gunman who climbed atop an unsecured roof and fired multiple shots from an AR-style rifle, wounding Trump, killing a rallygoer and seriously injuring two others.

The Secret Service this week confirmed that it had approved a new security plan that would use ballistic glass and other measures to increase Trump’s security at outdoor campaign events and to protect him onstage.

Sheets of ballistic glass are typically reserved for presidents and vice presidents, and are considered a major enhancement for a presidential candidate, according to a Secret Service official, who spoke on the condition of anonymity to discuss sensitive security measures. The Defense Department coordinates the provision of ballistic glass.

Harris would be given the same protection if needed, officials said.

Other measures, such as the increased use of drones, are also expected, though officials declined to provide details to avoid jeopardizing security.

Kimberly Cheatle resigned as the Secret Service director days after the July attack, after lawmakers from both parties urged her to step down.

Carol D. Leonnig and Josh Dawsey contributed to this report.