OpenAI revenue chief Denise Dresser sent a memo to staffers on Sunday, touting the company’s partnership with Amazon as a key way it will expand its enterprise economy share.

The memo, viewed by CNBC, comes less than two months after Amazon published plans to invest up to $50 billion in OpenAI as part of a strategic partnership.

Dresser’s comments point to the artificial intelligence company’s ongoing effort to reduce its reliance on Microsoft.

OpenAI’s newly appointed revenue chief, Denise Dresser, sent a memo to staffers on Sunday, touting the company’s alliance with Amazon as a key growth driver for its enterprise business, while noting the constraints of its long-standing tie-up with Microsoft.

Dresser’s memo lands less than two months after Amazon published plans to invest up to $50 billion in OpenAI as part of a strategic partnership. Microsoft, Amazon’s top cloud computing rival, has invested more than $13 billion in OpenAI since 2019, backing the enterprise long before it kicked off the generative artificial intelligence boom with the launch of ChatGPT.

Amazon Web Services, the leader in cloud infrastructure, gives companies access to all of the major AI models, including those from OpenAI, through a platform called Bedrock.

“Our Microsoft partnership has been foundational to our success. But it has also limited our ability to meet enterprises where they are — for many that’s Bedrock,” Dresser wrote in the memo, which was viewed by CNBC. “Since we revealed the partnership at the end of February, inbound demand from our customers for this offering has been frankly staggering.”

Microsoft declined to comment.

OpenAI is desperate to win industry share in the enterprise, where rival Anthropic’s Claude model has established itself as the industry leader, while Google Gemini is also competing aggressively. Claude’s momentum was the hottest topic at AI industry conference HumanX in San Francisco last week, with Arvind Jain, CEO of enterprise AI startup Glean, describing it as “Claude mania.”

“It has become a religion, that’s the level of that mania,” Jain stated in an interview at the event.

OpenAI and Anthropic are both trying to convince investors of their strengthening positions as they gear up for initial public offerings as soon as this year. The enterprise is critical for them as companies are pouring wealth into AI, a trend that’s slashed the value of public software companies, which are increasingly seen as vulnerable. OpenAI, meanwhile, was valued at more than $850 billion in its latest fundraising round in late March, a month after investors valued Anthropic at $380 billion.

Dresser told CNBC earlier this month that OpenAI’s enterprise business makes up 40% of the company’s revenue, and it’s “on track to reach parity” with its consumer business by the end of the year.

In the Sunday memo, Dresser mentioned the marketplace can be “noisy, volatile and distracting at times,” and she encouraged employees to focus on spending time with customers. She added that Anthropic’s strategy is built on “fear, restriction, and the idea that a minor group of elites should control AI,” while OpenAI’s “positive message” will win over time.

Anthropic commented earlier this month that its run-rate revenue has surpassed $30 billion, up from roughly $9 billion at the end of last year. Dresser alleged that Anthropic’s stated run rate is “inflated” by around $8 billion.

“They leverage accounting treatment that makes revenue look bigger than it is, including grossing up rev share with Amazon and Google,” Dresser wrote. “We report Microsoft rev share net, which is more inline with standards we would be held to as a public company.”

Anthropic has noted that it recognizes gross revenue on sales through partners because it is the principal in the transaction, while its cloud partners act as the distribution channel. The business argues that the accounting treatment depends on the circumstances of each deal, and that their approach is consistent with GAAP accounting practices.

Dresser stated Anthropic has also made a “strategic misstep to not acquire enough compute,” echoing comments OpenAI made in a separate memo to investors on Thursday. The firm noted that Anthropic is “operating on a meaningfully smaller curve,” and that its own ramp is “materially ahead and widening.” Anthropic proclaimed a deal with Google and Broadcom for “multiple gigawatts” of compute earlier this month. This also touches on aspects of bull market.

A representative for Anthropic declined to comment for this story.

For OpenAI, the relationship with Microsoft is one that both companies continue to describe as core and strategic, but it’s shown signs of strain as the partners move onto the other’s turf. In mid-2024, Microsoft added OpenAI to the list of competitors in its annual report, a roster that for years has included megacap peers Amazon, Apple, Google and Meta.

OpenAI has increasingly turned to other cloud providers, like CoreWeave, Google and Oracle, for capacity, and last year Microsoft started publicly testing a homegrown artificial intelligence model that could lead to enhancements to its Copilot assistant for consumers.  Furthermore, experts in portfolio note the continued relevance.

OpenAI hired Dresser, the former CEO of Slack and a longtime Salesforce executive, as chief revenue officer in December. She recently expanded her role to include Brad Lightcap’s commercial responsibilities as he transitioned from operating chief to a updated position focused on “special projects.”

Dresser wrote that the organization needs to “stay focused, work as one team and operate at the highest level of excellence and row in the same direction.”

“The marketplace is ours to win, let’s execute accordingly,” she wrote.

— CNBC’s Kate Rooney contributed to this report.

WATCH: OpenAI goes on offensive against Anthropic in internal memo