Vice President Pence’s trip to Arizona this week had to be postponed by a day after several Secret Service agents who helped organize the visit either tested positive for the coronavirus or were showing symptoms of being infected.

Pence was scheduled to go to Phoenix on Tuesday but went on Wednesday instead so that healthy agents could be deployed for his visit, according to two senior administration officials who spoke on the condition of anonymity to describe private details of the trip.

Arizona has seen a spike in cases in recent weeks, and Pence scaled back the trip before the delay because of the growing amount of infections in the state.

Pence’s staff was concerned last weekend about their ability to hold planned public events in Tucson and Yuma due to the outbreak, one administration official said, and decided on Saturday to limit the visit to Phoenix for a much smaller meeting — a public health briefing with Gov. Doug Ducey (R) and local health-care leaders.

On Monday night, the Secret Service urged Pence’s staff to delay the Tuesday trip until Wednesday because at least one agent on the ground had a confirmed case of covid-19 and other agents and federal officers preparing for the Arizona visit were showing signs of illness, according to two administration officials.

The Secret Service needed time to bring in healthy agents and other personnel to replace the ones who were either sick or most likely sick, one of the officials said. The official said the Secret Service estimated that a total of eight to 10 agents and other officers from sister agencies — all of whom were helping prepare for Pence’s visit to Arizona — had fallen ill.

This is the second time in recent weeks that Secret Service agents preparing for a White House or Trump campaign event outside Washington have contracted the virus. At least three Secret Service personnel working on the advance team for President Trump’s Tulsa rally on June 20 tested positive for the coronavirus. Two agents tested positive hours before the indoor stadium event was held, and dozens of agents who were on site for the rally were ordered to self-quarantine when they arrived home.

Trump was criticized for holding the rally in an area with an increasing number of cases, but he brushed aside the concerns raised by public health officials and urged his supporters to turn out. Far fewer people than expected attended the rally. Pence has faced criticism over his recent travels as he has sought to get out of Washington and visit areas hit hard by the coronavirus that are also key swing states in the upcoming election, such as Arizona and Florida.

A spokesperson for Pence, who heads the administration’s coronavirus task force, declined to address the specific issues of the trip’s delay.

“Instead of highlighting Vice President Pence’s concerted effort with Task Force members to visit and support states with new cases, The Washington Post is choosing to use its pages to report on a story of little use to every day Americans attempting to learn more about how coronavirus affects them or the Administration’s response efforts,” Pence spokesman Devin O’Malley said in a statement.

One administration official defended Pence’s trip to Arizona and said the vice president values traveling the country so he can see some of the hardest-hit areas, meet with state and local officials and have an informed opinion while showing the administration is paying attention. Pence traveled to Arizona with other administration officials, including Deborah Birx, the White House coronavirus response coordinator.

While in Phoenix, Pence was asked by a reporter why he needed to travel to Arizona to be briefed on the outbreak.

“Well, the rising cases here in Arizona is why I’m here. It’s why we brought the White House Coronavirus Task Force here,” Pence said. “I’m a real believer, as President Trump is, in — in sitting down with the people that are leading the effort.”

The heightened risk of agents getting sick while they try to prepare for events for Trump and Pence in cities far from Washington has begun to frazzle agents and their families, according to several people who have spoken to agents. The Secret Service’s foremost mission is protecting the safety and health of the president and vice president, as well as 39 members of their family and senior leaders in the administration.

Trump’s news conferences are typically broadcast live, and Pence could have communicated with the governor of Arizona and other local leaders through video conference.

Pence did not leave the airport during his Phoenix trip, which lasted about two and a half hours.

Many of the activities that the Centers for Disease Control and Prevention warn can increase the chance of infection are similar to what advance agents are required to do to plan the major events the White House and campaign have chosen to host. The agents must travel significant distances away from home, meet with strangers, and spend many hours indoors with other teams to coordinate security planning.

Secret Service communications director Catherine Milhoan declined to comment on any specifics on number of agents who were infected or steps taken to protect them, but she stressed that the agency follows CDC guidelines and issued the following statement.

“The health and safety of our workforce, their families, and that of our protectees remains the agency’s highest priority,” she said. “As a matter of practice, the Secret Service does not comment on the means and methods used to carry out our protective operations. The men and women of the Secret Service continue to meet operational mission requirements without fail.”

Despite the illnesses that were found among advance team members at the president’s June 20 rally in Tulsa, Pence’s office soldiered forward to try to hold events in Arizona.

The White House has said that Trump and Pence are tested daily for infection.

At the Tulsa event, six advance team members tested positive in the hours before the rally, which was reported by media outlets that afternoon. The news set off a scramble by the campaign to determine if the tests had been flawed, but also to quiz health care workers conducting the tests about whether they had leaked the information to the media. Two Secret Service personnel — an advance agent and an officer in charge of screening rally attendees — also tested positive that day.

Later, a group of Secret Service agents in the Tulsa field office arranged to be discreetly tested in the parking lot of a hospital, avoiding the normal routine of entering the emergency room and answering questions about their potential exposure, according to two people familiar with the agency’s decision. Dozens of Secret Service agents on the Tulsa trip were instructed to self-quarantine at home for two weeks when they returned from Tulsa.