A CNBC analysis of House disbursement records has found that ChatGPT is by far the most-used AI tool among US Congressional offices, accounting for roughly 90% of all AI-related spending. The finding highlights how quickly generative AI has become embedded in the day-to-day work of Congressional staff, who use it for tasks ranging from drafting memos to analysing legislation.

Between April 2025 and March 2026, Congress spent around $100,580 across 798 transactions on ChatGPT, out of at least $113,740 in total AI spending, with Anthropic's Claude a distant second at $13,160 across 37 transactions. Democratic offices spent roughly three times as much on AI tools as Republican ones ($54,165 versus $15,782). The figures exclude free accounts or AI tools bundled into wider software contracts, and staffers reportedly use these tools to write memos, summarise and analyse legislation, respond to constituents, prepare hearing materials, conduct policy research and draft social media posts.