Sen. Ron Wyden (D-OR), the top Democrat on the Senate’s tax-writing panel, is proposing a tax on new data centers, the latest sign of rising political headwinds to the massive build-out of the facilities, which are crucial to the advancement of artificial intelligence.

Wyden, the ranking member of the Senate Finance Committee, announced the pitch on Thursday as a five-page white paper and is asking the public for feedback on the proposal. The plan doesn’t include specific details of how much the data centers would be taxed, but provides contours and lays the groundwork for a legislative push.