Chris Christie, the former governor of New Jersey who for several days this week helped the president prepare for the debate, said he tested positive for the coronavirus.
Mr. Christie announced his condition on Saturday, becoming the last of several Trump associates to claim he tested positive for the virus.
“I want to thank all my friends and colleagues who have contacted to ask how I was feeling over the past day or two,” he he said on Twitter.
“Even though I feel fine and have only mild symptoms, due to my history of asthma we have decided that this is an important precautionary measure,” she said.
Christie’s statement came a day after President Trump’s campaign manager Bill Stepien tested positive for the virus.
Mr. Stepien, who was with Mr. Trump at the presidential debate in Cleveland on Tuesday, is experiencing mild symptoms and is in solitary confinement, according to a person briefed on the matter.
Mr. Christie and Mr. Stepien were among the numerous advisors who huddled with Mr. Trump and others to prepare for the Sunday through Tuesday debate.
That group also included Hope Hicks, one of Trump’s closest advisers, and Kellyanne Conway, a former White House senior aide, both of whom have tested positive ever since.
Nobody wore masks during the prep, Mr. Christie said.
Ms. Conway and Mr. Christie also attended an event at the White House on September 26 announcing Mr. Trump’s Supreme Court nominee, Judge Amy Coney Barrett.
Others who attended and said they tested positive include Senator Mike Lee, a Republican from Utah; Senator Thom Tillis, Republican of North Carolina; and the Rev. John I. Jenkins, the president of the University of Notre Dame.