In a fast-moving sequence of events, Altman, who was ousted by the board last week, has now been hired by Microsoft where he will take the lead in developing a new advanced AI research team.
In a letter released to media, the vast majority of OpenAI's 770-strong staff suggested they would follow Altman unless the board responsible for his departure resigned.
"Your actions have made it obvious that you are incapable of overseeing OpenAI," the letter said. "Microsoft has assured us that there are positions for all OpenAI employees at this new subsidiary should we choose to join."
Among the signatories was Ilya Sutskever, the company's chief scientist and a member of the four-person board who pushed Altman out.
"I deeply regret my participation in the board’s actions," Sutskever said in a post on X. "I never meant to harm OpenAI.
Another signatory was top executive Mira Murati, who was appointed to replace Altman as CEO when he was removed, but was herself cast aside for the job over the weekend.
Staff members posted on social media that up to 90% of OpenAI's employees signed the letter.
"We have more unity and commitment and focus than ever before. We are all going to work together some way or other, and I’m so excited," Altman said on X.
OpenAI has appointed Emmett Shear, a former chief executive of Amazon's streaming platform Twitch, as its new CEO despite pressure from Microsoft and other major investors to reinstate Altman.
After the startup's board sacked Altman, US media cited concerns that he was underestimating the dangers of its tech and leading the company away from its stated mission—claims his successor has denied.
Microsoft CEO Satya Nadella wrote on X that Altman "will be joining Microsoft to lead a new advanced AI research team," along with OpenAI co-founder Greg Brockman and other colleagues.
Global tech titan Microsoft has invested more than $10 billion in OpenAI and has rolled out the AI pioneer's tech in its own products.
Microsoft's Nadella added in his post that "we look forward to getting to know Emmett Shear and OAI's new leadership team and working with them."
"We remain committed to our partnership with OpenAI and have confidence in our product roadmap," he said.
But a key AI executive at Microsoft confirmed that they all were welcome from OpenAI if the board that removed Altman doesn't resign.
"I know that some people are going to hate me for this, but this is the best show I've seen in my life," added Miguel Fierro, the tech giant's Principal Data Scientist Manager.
Altman shot to fame with the launch of ChatGPT last year, which ignited a race to advance AI research and development, as well as billions being invested in the sector.
His sacking triggered several other high-profile departures from the company, as well as a reported push by investors to bring him back.
But OpenAI stood by its decision in a memo sent to employees on Sunday night, saying "Sam's behavior and lack of transparency... undermined the board's ability to effectively supervise the company."
'Badly' handled sacking
Shear confirmed his appointment as OpenAI's interim CEO in a post on X, while also denying reports that Altman had been fired over safety concerns regarding the use of AI technology.
"Today I got a call inviting me to consider a once-in-a-lifetime opportunity: to become the interim CEO of @OpenAI. After consulting with my family and reflecting on it for just a few hours, I accepted," he wrote.
"It's clear that the process and communications around Sam's removal has been handled very badly, which has seriously damaged our trust," Shear added.
Generative AI platforms such as ChatGPT are trained on vast amounts of data to enable them to answer questions, even complex ones, in human-like language.
They are also used to generate and manipulate imagery.
But the tech has triggered warnings about the dangers of its misuse—from blackmailing people with "deepfake" images to the manipulation of images and harmful disinformation. (AFP)