Among AI tools, no product appeared in more identifiable House spending than ChatGPT.
From April 1, 2025, through March 31, 2026, CNBC found at least $113,740 in payments to named AI vendors. Of that amount, ChatGPT represented $100,580 spread over 798 transactions. Anthropic's Claude, the runner-up, totaled $13,160 across 37 transactions.
By volume, ChatGPT's dominance was even sharper: 96% of reviewed transactions were for the tool. The 71 House member offices split as 44 Democratic and 27 Republican.
ChatGPT's lead is mostly a first-mover story.
In 2023, the House Digital Service stood up an AI working group and handed out an initial batch of 40 ChatGPT Plus accounts to a bipartisan set of staffers.
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OpenAI worked with the nonpartisan Congressional Management Foundation to train congressional staff. OpenAI engineers helped lead part of the program.
Marci Harris, who leads the POPVOX Foundation, said ChatGPT was so familiar in the early days that it was almost synonymous with AI, "the way Kleenex is with tissues or Band-Aid is with bandages."
The 2023 working group gave congressional offices an approved channel for trying ChatGPT. By the time House leaders published stricter AI-use rules in September 2024, ChatGPT was already the first AI tool many offices recognized by name.
Rep. Julie Fedorchak (R-N.D.) described her office's old routine: staffers would invest long stretches in drafting briefing memos for the more than a dozen meetings she faced each day, leaving less time for legislative work. Now, she explained, she and her team rely on ChatGPT to maintain a searchable database of her legislation and of materials from constituents and outside groups. Using AI to turn that material into memos, she said, is "saving dozens and dozens of hours every week of staff time."
Rep. James Walkinshaw (D-Va.) says his office applies AI broadly - research, social media, newsletters - but staff must verify every fact and decisions remain human. "Our caseworkers in our district office can use AI to help organize casework requests, maybe expedite them, move things along faster," he told CNBC. "But when they're making decisions related to a constituent's case - are we going to advocate for our constituent with the Social Security Administration or with IRS? - that has to be a human decision, not an AI decision."
The official totals almost certainly understate how much Congress uses AI. The review only covers payments where House disbursement records explicitly list an AI vendor. That leaves out free accounts, AI capabilities embedded in wider software agreements such as Microsoft Copilot, reimbursements that lack vendor details, and the Senate - whose public spending disclosures don't specify software providers the same way. Senate rules bar Claude for official use.
Samantha Carter, chief communications officer for the House Chief Administrative Officer's office, said the House's AI approach "is deliberately not limited to a single vendor."
Harris added that the House's rollout of Microsoft Copilot could account for more official AI expenditure than the ChatGPT payments shown in public records.
The stakes extend beyond making congressional offices more efficient. Across Washington, OpenAI, Anthropic, Google and Microsoft are competing for sway as Congress and federal agencies determine how AI tools should be bought, used and overseen.
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