Ms. Di Lauro, the former strategist in Nevada, was emphatic in her own Facebook posts. “I have to speak up about this now because I hope it will be of service to the next Sanders campaign,” she wrote on Dec. 7.

In her interview with The Times, Ms. Di Lauro said she told several people who were high up in the campaign, including Rich Pelletier, who served as national field director, about her encounter in Nevada with the surrogate, a Mexican game show host named Marco Antonio Regil. But she felt she was not taken seriously by the campaign.

“It was as if nothing happened,” she said.

Masha Mendieta, who was also on the Latino outreach team and who was with Ms. Di Lauro when she spoke with Mr. Velazquez about the incident, confirmed his comments.

Mr. Velazquez said he does not recall making the flippant remark to Ms. Di Lauro and that he took her complaint seriously. He said he assigned two women to accompany the surrogate, and he checked in with them to make sure there were no problems.

Mr. Regil said through his agent that he was honored to be a campaign surrogate for Mr. Sanders. “I sincerely apologize for any interactions or behavior on my part that could’ve made anyone feel uncomfortable,” he said.

Mr. Velasquez said he also told his boss, Arturo Carmona, another manager on the Latino outreach team and deputy national political director, about what had happened and followed up with a memo to Mr. Carmona two weeks later, detailing the incident in an email and saying that he believed Ms. Di Lauro.

Mr. Carmona said in an email to The Times that, after Mr. Velazquez notified him about the incident, he reported it to Mr. Pelletier.