OpenAI's ChatGPT has emerged as the dominant AI platform in the U.S. House of Representatives, capturing the overwhelming majority of official AI expenditures. Disbursement records analyzed by CNBC reveal a stark concentration of spending that underscores how quickly generative AI has become embedded in legislative workflows. Main Developments House offices, committees, and institutional accounts directed roughly 90% of all AI tool spending to OpenAI during the year ending March 31. The figures show approximately $100,580 flowing to ChatGPT across 798 separate transactions, representing the bulk of at least $113,740 in total AI-related expenditures. Read also: Wispr Flow's Updated Terms Hint at Meeting Notetaker Launch Anthropic's Claude trailed significantly in second place, receiving $13,160 across 37 transactions. The spending disparity highlights a clear preference for ChatGPT among congressional staffers when compared to competing AI platforms. Background Partisan differences in AI adoption are notable, with Democratic offices spending $54,165 on AI purchases—more than three times the $15,782 spent by Republican offices. The data captures only paid subscriptions and transactions, excluding free account usage or AI capabilities bundled within broader software contracts. Congressional staffers report using these tools for a range of substantive tasks. Common applications include drafting memos, summarizing and analyzing legislation, responding to constituent inquiries, preparing hearing materials, conducting policy research, and composing social media posts. Why It Matters The spending patterns signal a foundational shift in how legislative work gets accomplished, with AI tools now serving as standard infrastructure rather than experimental technology. The significant lead OpenAI holds suggests institutional momentum that could shape procurement decisions for years to come. Disparities between party spending may also reflect different attitudes toward AI adoption or varying operational needs across offices. These early purchasing patterns could influence how AI vendors tailor their government offerings and pricing structures. What's Next As congressional adoption matures, observers will likely track whether spending diversifies across multiple AI providers or consolidates further around ChatGPT. The current data represents a snapshot through March 31, leaving open questions about how usage patterns evolve in subsequent reporting periods.