Bret Taylor, the chairman of OpenAI’s board, said the artificial intelligence company was “not for sale.” Mr. Musk is separately raising money for his A.I. start-up, xAI.

Sam Altman is leaving no room for doubt about his views on an Elon Musk-led bid to take control of OpenAI. In a letter to OpenAI staff Monday, the CEO put the words “bid” and “deal” in scare quotes and said the startup’s board has no interest in the offer.

The board of OpenAI, the company behind ChatGPT, has received an offer from Elon Musk and investors to purchase the company.