Talks at OpenAI to bring back Sam Altman, the artificial intelligence start-up’s recently ousted chief executive, continued on Sunday afternoon but there were disagreements over the makeup of the company’s board of directors, according to two people familiar with the discussions.

Mr. Altman, 38, spent the weekend waging a pressure campaign on the start-up’s four-person board of directors who ousted him on Friday afternoon, three people familiar with the matter said. The result was a groundswell of support from investors, employees and OpenAI executives.

Mr. Altman was at the OpenAI headquarters on Sunday afternoon. He posted a photo of himself on X, formerly Twitter, wearing a guest identification badge and said, “first and last time am ever wear one of these.”

The negotiations included a look at how the company’s board of directors might be reshaped if Mr. Altman returns as chief executive, two of the people said. Members of the board have not yet agreed to what a restructured board of directors might look like — nor is Mr. Altman’s reinstatement an inevitability, two of the people said.