Two forces hit the AI infrastructure buildout this week. One came from Capitol Hill. The other came from substation yards across the country.
Senator Bernie Sanders introduced the Artificial Intelligence Data Center Moratorium Act, a federal bill that would halt new AI data center construction until Congress enacts AI safety and environmental review legislation. Representative Alexandria Ocasio-Cortez is a co-sponsor. The bill was announced April 29, 2026, and is pending committee action. It is proposed legislation, not law, not enacted, not in effect.
At the same time, Bloomberg reports that more than half of planned 2026 US data center builds are on hold. The culprit is a shortage of electrical transformers and switchgear, the unglamorous hardware that actually connects a data center to the power grid. That figure directionally aligns with a separate estimate from April: satellite analysis suggested roughly 40% of US AI data center builds were behind schedule at that point. The gap between those two figures likely reflects continued deterioration, though they use different methodologies.
Why this matters to infrastructure investors and capital allocators: the $700 billion in data center capex that hyperscalers have committed to this decade requires physical infrastructure that the supply chain cannot currently deliver at scale. BlackRock, Blackstone, and the major cloud providers are all exposed. Legislative risk adds a second ceiling on top of the physical one. These constraints are independent, the transformer shortage exists regardless of whether the Sanders bill passes, and the bill would constrain development regardless of whether supply chains recovered.
The Maine precedent is worth noting. In April 2026, Maine became the first US state to pass an AI data center moratorium, pending the governor’s signature at the time. Reports indicate as many as 12 states are now considering similar legislation, according to industry monitoring sources, a figure that hasn’t been independently confirmed but is consistent with the escalating pattern of state-level resistance to large-scale siting. The Sanders bill represents the first attempt to move that state-level resistance to the federal level.
This is the third consecutive month of federal legislative attention to AI data center power demand. A House subcommittee convened on the topic on April 29. The Maine moratorium passed April 18. Now a federal moratorium bill has arrived May 2. The legislative calendar and the supply chain deterioration are converging on the same problem from different directions, and neither is waiting for the other.
What to watch: committee assignment and co-sponsor count for the Sanders bill will signal whether this has meaningful legislative traction or functions primarily as political positioning. On the supply chain side, transformer lead times are the number to track, current industry estimates put custom transformer delivery at 2 to 3 years in some cases, which means builds approved today face physical constraints independent of any political outcome.
The TJS read: infrastructure investors who modeled their data center thesis on capital availability and permitting timelines now have a third variable to price in, physical input availability. The supply chain constraint is arguably more binding in the near term than the legislative risk. But the legislative risk is what makes the supply chain constraint permanent-looking rather than cyclical.